Patent Application
20060264509
The invention relates to methods for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome using smooth muscle modulators and α2δ subunit calcium channel modulators.
Pain is one of the most common medical complaints in the U.S. and one of the most prevalanet resaons for patients to seek medical attention (see, e.g., Bartel J, Beasley J, Berry P H, et al. Approaches to Pain Management. Oakbrook Terrace, Ill.: Joint Commission on the Accreditation of Healthcare Organizations; 2003). According to a 1999 Gallup survey reported by the Arthritis Foundation, 89% of Americans age 18 or older suffer pain at least once a month, with 42% of adults experiencing pain every day (see “Pain in America: highlights from a Gallup survey.” Arthritis Foundation [Web site]. Jun. 9, 1999). Pain also disproportionately affects women and the elderly, with women more likely to experience pain daily than men (46% versus 37%, respectively), and Americans aged 65 and older more likely to experience weekly pain than Americans aged 18 to 34 (75% versus 66%, respectively).
Pain is often treated by drug therapy, including analgesics, corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), antidepressants, topical anesthetics, local anesthetic injections, and electrical stimulation regimens. In particular, tricyclic antidepressants have been utilized to activate some of the descending pathways in the brain and spinal cord that provide analgesia, and opioids have been delivered directly to the cerebrospinal fluid for the treatment of pain in cancer patients. However, many of these treatments have undesireable side effects that limit their usefulness. For example, the side effects of opioids include the risk of respiratory depression, constipation, nausea, pruritis and sedation. In addition, opioids are psychologically and physically addictive. By contrast, nonsteroidal agents are associated with gastrointestinal upset, bleeding and kidney injury, while other agents and regimens may not provide adequate relief for the severity and type of pain sought to be treated.
Because existing therapies and treatments for pain have limited efficacy and are associated with side effects that result in reduced patient compliance, the present invention presents a significant advantage over these treatments via increased efficacy and decreased side effects. Because detrimental side effects are lessened, the present invention also has the benefit of improving patient compliance.
Compositions and methods for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome, are provided. Compositions of the invention comprise α2δ subunit calcium channel modulators in combination with one or more compounds with smooth muscle modulatory effects. According to the present invention, α2δ subunit calcium channel modulators include GABA analogs (e.g., gabapentin and pregabalin), fused bicyclic or tricyclic amino acid analogs of gabapentin, and amino acid compounds. Compounds with smooth muscle modulatory effects include antimuscarinics, β3 adrenergic agonists, spasmolytics, neurokinin receptor antagonists, bradykinin receptor antagonists, and nitric oxide donors. Compositions of the invention include combinations of the aforementioned compounds as well as pharmaceutically acceptable, pharmacologically active acids, salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof.
The compositions are administered in therapeutically effective amounts to a patient in need thereof for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. It is recognized that the compositions may be administered by any means of administration as long as an effective amount for the treatment of pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome, is delivered. The compositions may be formulated, for example, for sustained, continuous, or as-needed administration.
One advantage of the present invention is that at least one detrimental side effect associated with single administration of an α2δ subunit calcium channel modulator or a smooth muscle modulator is lessened by concurrent administration of an α2δ subunit calcium channel modulator with a smooth muscle modulator. When an α2δ subunit calcium channel modulator is administered in combination with a smooth muscle modulator, less of each agent is needed to achieve therapeutic efficacy. Because current treatments for pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome have limited efficacy and are associated with side effects that result in reduced patient compliance, the present invention presents a significant advantage over these treatments via increased efficacy and decreased side effects. Because detrimental side effects are lessened, the present invention also has the benefit of improving patient compliance.
Overview and Definitions
The present invention provides compositions and methods for treating pain. The compounds and methods of the present invention may be used to treat any type of pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. The compositions comprise a therapeutically effective dose of a compound with smooth muscle modulatory effects in combination with an α2δ subunit calcium channel modulator, such as gabapentin or pregabalin. Compounds with smooth muscle modulatory effects include, but are not limited to, antimuscarinics, β3 adrenergic agonists, spasmolytics, neurokinin receptor antagonists, bradykinin receptor antagonists, and nitric oxide donors. The methods are accomplished by administering, for example, a compound with smooth muscle modulatory effects, such as oxybutynin, in combination with an α2δ subunit calcium channel modulator and/or another compound that interacts with α2δ subunit-containing calcium channels, such as gabapentin or pregabalin. For these methods, various compositions and formulations that contain quantities of a compound with smooth muscle modulatory effects in combination with an α2δ subunit calcium channel modulator and/or other compounds that interact with α2δ subunit-containing calcium channels are encompassed.
It is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
It must be noted that as used in this specification and the appended embodiments, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an active agent” or “a pharmacologically active agent” includes a single active agent as well as two or more different active agents in combination, reference to “a carrier” includes mixtures of two or more carriers as well as a single carrier, and the like.
By “pain” is intended an unpleasant sensation occurring in varying degrees of severity as a consequence of injury, disease, or emotional disorder. It is usually associated with actual or potential tissue damage. Pain can be classified as either acute or chronic. By “acute pain” is intended pain “caused by a noxious stimulus due to an injury, a disease process, or an abnormally functioning muscle or viscera” (Russo (2001) Pain: Control. In Encyclopedia of Life Sciences. London: Nature Publishing Group, http://www.els.net). Acute pain includes pain that lasts for up to 3 months, including pain that lasts for up to about 2.5 months, up to about 2 months, up to about 1.5 months, up to about 1 month, up to about 3 weeks, up to about 2 weeks, up to about 1 week, up to about 6 days, up to about 5 days, up to about 4 days, up to about 3 days, up to about 2 days, up to about 1 day. By “chronic pain” is intended pain that lasts for three months or longer (See, e.g., Family Practice, Vo. 18, No. 3, p. 292-299 (2001)). Acute pain can be subdivided into nociceptive pain and neuropathic pain. By “nociceptive pain” is intended pain that results from the activation of nociceptors in the skin or soft tissue in response to injury. Pain resulting from the activation of somatic primary afferents is termed “somatic pain.” This type of pain is usually described as aching, squeezing, stabbing or throbbing. Pain resulting from the stimulation of afferent receptors in the viscera is termed “visceral pain.” This type of pain is often described as cramping or gnawing (“Pain Management: Pathophysiology of Pain and Pain Assessment” (2003) American Medical Association Continuing Medical Education Program). By “chronic pelvic pain” is intended a syndrome characterized by clinical assessment of pain in the pelvic region that is chronic in nature (J. Gunter, Obstet. Gynecol. Surv., 58: 615-23 (2903)).
By “neuropathic pain” is intended pain initiated or caused by direct injury to nerves in the peripheral or central nervous system. Neuropathic pain includes reflex sympathetic dystrophy, postherpetic neuralgia, which occurs in some patients after shingles, phantom limb pain, and anesthesia dolorosa (pain in the absence of sensation) (Basbaum and Jessell (2000) The Perception of Pain. In Principles of Neural Science, 4th. Ed. pp. 472-491). By “neurogenic pain” is intended pain that originates in the nervous system. By “psychogenic pain” is intended chronic pain without definite organic pathology. Neuropathic and psychogenic pain may develop without impending tissue damage. Neuropathic pain typically occurs following injury to elements of the nervous system involved in nociception, such as peripheral nerve injury, in which the lesions deafferent the nociceptive pathway. By “deafferentation pain” is intended pain that results from the removal of the afferent pain signal. By “referred pain” is intended pain from injury to a visceral organ that is displaced to another area of the body.
Types of abnormal pain include allodynia, which is defined as a condition in which ordinarily nonpainful stimuli evoke pain, and hyperalgesia, which is defined as an excessive response to noxious stimuli. Hyperalgesia results both from peripheral sensitization of nociceptors and an increased excitability of central nociceptive neurons (Craig and Sorkin (2001) Pain and Analgesia. In Encyclopedia of Life Sciences. London: Nature Publishing Group, http:/www.els.net). Inflammatory hyperalgesia is involved in many diseases with symptomatic pain, including arthritis (Craig and Sorkin (2001) Pain and Analgesia. In Encyclopedia of Life Sciences. London: Nature Publishing Group, http:/www.els.net). “Hyperpathia” is an exaggerated response to a painful stimulus in which the sensation of pain continues after the stimulation has ceased.
By “prostatitis” is intended any type of disorder associated with an inflammation of the prostate, including chronic bacterial prostatitis and chronic non-bacterial prostatitis. By “non-painful prostatitis” is intended prostatitis involving sensations or symptoms, including mild or general discomfort, that a patient subjectively describes as not producing or resulting in pain. By “painful prostatitis” is intended prostatitis involving sensations or symptoms that a patient subjectively describes as producing or resulting in pain.
“Chronic bacterial prostatitis” is used in its conventional sense to refer to a disorder associated with symptoms that include inflammation of the prostate and positive bacterial cultures of urine and prostatic secretions. “Chronic non-bacterial prostatitis” is used in its conventional sense to refer to a disorder associated with symptoms that include inflammation of the prostate and negative bacterial cultures of urine and prostatic secretions. “Prostadynia” is used in its conventional sense to refer to a disorder generally associated with painful symptoms of chronic non-bacterial prostatitis as defined above, without inflammation of the prostate.
“Interstitial cystitis” is used in its conventional sense to refer to a disorder associated with symptoms that include irritative voiding symptoms, urinary frequency, urgency, nocturia, and suprapubic or pelvic pain related to and relieved by voiding.
“Vulvodynia” is used in its conventional sense to refer to a condition characterized by gynecologic syndrome characterized by unexplained vulvar pain, sexual dysfunction, and psychological disability.
“Vulvar vestibulitis” (also known as “vulvar vestibulitis syndrome,” “focal vulvitis,” and “vestibular adenitis”) is used in its conventional sense to refer to a condition that is a subtype of vulvodynia characterized by: 1) pain on vestibular touch or attempted vaginal entry; 2) tenderness to Q-tip pressure localized within the vulvar vestibule; 3) physical findings confined to vestibular erythema of various degrees; and 4) an exclusion of other causes for vestibular erythema and tenderness, such as candidiasis (yeast infections) or herpes infections. Other symptoms may include itching, swelling and excoriation.
The terms “active agent” and “pharmacologically active agent” are used interchangeably herein to refer to a chemical compound that induces a desired effect, i.e., in this case, treatment of pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, as well as pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. The primary active agents herein are α2δ subunit calcium channel modulators and/or smooth muscle relaxants. The present invention comprises a therapy wherein a smooth muscle modulator is administered in combination with an α2δ subunit calcium channel modulator. Combination therapy may be carried out by administration of the different active agents in a single composition, by concurrent administration of the different active agents in different compositions, or by sequential administration of the different active agents. The combination therapy may also include situations where the α2δ subunit calcium channel modulator or the smooth muscle modulator is already being administered to the patient, and the additional component is to be added to the patient's drug regimen, as well as where different individuals (e.g., physicians or other medical professionals) are administering the separate components of the combination to the patient. Included are derivatives and analogs of those compounds or classes of compounds specifically mentioned that also induce the desired effect.
The term “α2δ subunit calcium channel modulator” as used herein refers to an agent that is capable of interacting with the α2δ subunit of a calcium channel, including a binding event, including subtypes of the α2δ calcium channel subunit as disclosed in Klugbauer et al. (1999) J. Neurosci. 19: 684-691, to produce a physiological effect, such as opening, closing, blocking, up-regulating functional expression, down-regulating functional expression, or desensitization, of the channel. Unless otherwise indicated, the term “α2δ subunit calcium channel modulator” is intended to include GABA analogs (e.g., gabapentin and pregabalin), fused bicyclic or tricyclic amino acid analogs of gabapentin, amino acid compounds, and other compounds that interact with the α2δ calcium channel subunit as disclosed further herein, as well as acids, salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof. Further, it is understood that any salts, esters, amides, prodrugs, active metabolites or other derivatives are pharmaceutically acceptable as well as pharmacologically active. Gabapentin and pregabalin are preferred α2δ subunit calcium channel modulator for use in the methods of the present invention.
The term “peptidomimetic” is used in its conventional sense to refer to a molecule that mimics the biological activity of a peptide but is no longer peptidic in chemical nature, including molecules that lack amide bonds between amino acids, as well as pseudo-peptides, semi-peptides and peptoids. Peptidomimetics according to this invention provide a spatial arrangement of reactive chemical moieties that closely resembles the three-dimensional arrangement of active groups in the peptide on which the peptidomimetic is based. As a result of this similar active-site geometry, the peptidomimetic has effects on biological systems that are similar to the biological activity of the peptide.
The term “smooth muscle modulator” as used herein refers to any compound that inhibits or blocks the contraction of smooth muscles, including but not limited to antimuscarinics, β3 adrenergic agonists, spasmolytics, neurokinin receptor antagonists, bradykinin receptor antagonists, and nitric oxide donors. Smooth muscle modulators can be “direct” (also known as “musculotropic”) or “indirect” (also known as “neurotropic”). “Direct smooth muscle modulators” are smooth muscle modulators that act by inhibiting or blocking contractile mechanisms within smooth muscle, including but not limited to modification of the interaction between actin and myosin. “Indirect smooth muscle modulators” are smooth muscle modulators that act by inhibiting or blocking neurotransmission that results in the contraction of smooth muscle, including but not limited to blockade of presynaptic facilitation of acetylcholine release at the axon terminal of motor neurons terminating in smooth muscle. A preferred smooth muscle modulator for the present invention is oxybutynin.
The term “anticholinergic agent” as used herein refers to any acetylcholine receptor antagonist, including antagonists of nicotinic and/or muscarinic acetylcholine receptors. The term “antinicotinic agent” as used herein is intended any nicotinic acytylcholine receptor antagonist. The term “antimuscarinic agent” as used herein is intended any muscarinic acetylcholine receptor antagonist. Unless otherwise indicated, the terms “anticholinergic agent,” “antinicotinic agent,” and “antimuscarinic agent” are intended to include anticholinergic, antinicotinic, and antimuscarinic agents as disclosed further herein, as well as acids, salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof. Further, it is understood that any acids, salts, esters, amides, prodrugs, active metabolites or other derivatives are pharmaceutically acceptable as well as pharmacologically active.
The term “β3 adrenergic agonist” is used in its conventional sense to refer to a compound that binds to and agonizes β3 adrenergic receptors. Unless otherwise indicated, the term “β3 adrenergic agonist” is intended to include β3 adrenergic agonist agents as disclosed further herein, as well as acids salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof. Further, it is understood that any acids salts, esters, amides, prodrugs, active metabolites or other derivatives are pharmaceutically acceptable as well as pharmacologically active.
The term “spasmolytic” (also known as “antispasmodic”) is used in its conventional sense to refer to a compound that relieves or prevents muscle spasms, especially of smooth muscle. Unless otherwise indicated, the term “spasmolytic” is intended to include spasmolytic agents as disclosed further herein, as well as acids, salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof. Further, it is understood that any acids, salts, esters, amides, prodrugs, active metabolites or other derivatives are pharmaceutically acceptable as well as pharmacologically active.
The term “neurokinin receptor antagonist” is used in its conventional sense to refer to a compound that binds to and antagonizes neurokinin receptors. Unless otherwise indicated, the term “neurokinin receptor antagonist” is intended to include neurokinin receptor antagonist agents as disclosed further herein, as well as acids salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof. Further, it is understood that any acids, salts, esters, amides, prodrugs, active metabolites or other derivatives are pharmaceutically acceptable as well as pharmacologically active.
The term “bradykinin receptor antagonist” is used in its conventional sense to refer to a compound that binds to and antagonizes bradykinin receptors. Unless otherwise indicated, the term “bradykinin receptor antagonist” is intended to include bradykinin receptor antagonist agents as disclosed further herein, as well as acids, salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof. Further, it is understood that any acids, salts, esters, amides, prodrugs, active metabolites or other derivatives are pharmaceutically acceptable as well as pharmacologically active.
The term “nitric oxide donor” is used in its conventional sense to refer to a compound that releases free nitric oxide when administered to a patient. Unless otherwise indicated, the term “nitric oxide donor” is intended to include nitric oxide donor agents as disclosed further herein, as well as acids, salts, enantiomers, analogs, esters, amides, prodrugs, active metabolites, and derivatives thereof. Further, it is understood that any acids, salts, esters, amides, prodrugs, active metabolites or other derivatives are pharmaceutically acceptable as well as pharmacologically active.
The terms “treating” and “treatment” as used herein refer to relieving pain including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome as described herein.
By an “effective” amount or a “therapeutically effective amount” of a drug or pharmacologically active agent is meant a nontoxic but sufficient amount of the drug or agent to provide the desired effect, i.e., relieving pain including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome, as explained above. It is recognized that the effective amount of a drug or pharmacologically active agent will vary depending on the route of administration, the selected compound, and the species to which the drug or pharmacologically active agent is administered, as well as the age, weight, and sex of the individual to which the drug or pharmacologically active agent is administered. It is also recognized that one of skill in the art will determine appropriate effective amounts by taking into account such factors as metabolism, bioavailability, and other factors that affect plasma levels of a drug or pharmacologically active agent following administration within the unit dose ranges disclosed further herein for different routes of administration.
By “pharmaceutically acceptable,” such as in the recitation of a “pharmaceutically acceptable carrier,” or a “pharmaceutically acceptable acid addition salt,” is meant a material that is not biologically or otherwise undesirable, i.e., the material may be incorporated into a pharmaceutical composition administered to a patient without causing any undesirable biological effects or interacting in a deleterious manner with any of the other components of the composition in which it is contained. “pharmacologically active” (or simply “active”) as in a “pharmacologically active” derivative or metabolite, refers to a derivative or metabolite having the same type of pharmacological activity as the parent compound. When the term “pharmaceutically acceptable” is used to refer to a derivative (e.g., a salt or an analog) of an active agent, it is to be understood that the compound is pharmacologically active as well, i.e., therapeutically effective for treating pain.
By “continuous” dosing is meant the chronic administration of a selected active agent.
By “as-needed” dosing, also known as “pro re nata” “prn” dosing, and “on demand” dosing or administration is meant the administration of a single dose of the active agent at some time prior to commencement of an activity wherein suppression of pain would be desirable. Administration can be immediately prior to such an activity, including about 0 minutes, about 10 minutes, about 20 minutes, about 30 minutes, about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, or about 10 hours prior to such an activity, depending on the formulation.
By “short-term” is intended any period of time up to and including about 8 hours, about 7 hours, about 6 hours, about 5 hours, about 4 hours, about 3 hours, about 2 hours, about 1 hour, about 40 minutes, about 20 minutes, or about 10 minutes after drug administration.
By “rapid-offset” is intended any period of time up to and including about 8 hours, about 7 hours, about 6 hours, about 5 hours, about 4 hours, about 3 hours, about 2 hours, about 1 hour, about 40 minutes, about 20 minutes, or about 10 minutes after drug administration.
The term “controlled release” is intended to refer to any drug-containing formulation in which release of the drug is not immediate, i.e., with a “controlled release” formulation, oral administration does not result in immediate release of the drug into an absorption pool. The term is used interchangeably with “non-immediate release” as defined in Remington: The Science and Practice of Pharmacy, Twentieth Ed. (Philadelphia, Pa.: Lippincott Williams & Wilkins, 2000).
The “absorption pool” represents a solution of the drug administered at a particular absorption site, and kr, ka, and ke are first-order rate constants for: 1) release of the drug from the formulation; 2) absorption; and 3) elimination, respectively. For immediate release dosage forms, the rate constant for drug release kr is far greater than the absorption rate constant ka. For controlled release formulations, the opposite is true, i.e., kr<<<ka, such that the rate of release of drug from the dosage form is the rate-limiting step in the delivery of the drug to the target area. The term “controlled release” as used herein includes any nonimmediate release formulation, including but not limited to sustained release, delayed release and pulsatile release formulations.
The term “sustained release” is used in its conventional sense to refer to a drug formulation that provides for gradual release of a drug over an extended period of time, and that preferably, although not necessarily, results in substantially constant blood levels of a drug over an extended time period such as up to about 72 hours, about 66 hours, about 60 hours, about 54 hours, about 48 hours, about 42 hours, about 36 hours, about 30 hours, about 24 hours, about 18 hours, about 12 hours, about 10 hours, about 8 hours, about 7 hours, about 6 hours, about 5 hours, about 4 hours, about 3 hours, about 2 hours, or about 1 hour after drug administration.
The term “delayed release” is used in its conventional sense to refer to a drug formulation that provides for an initial release of the drug after some delay following drug administration and that preferably, although not necessarily, includes a delay of up to about 10 minutes, about 20 minutes, about 30 minutes, about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, or about 12 hours.
The term “pulsatile release” is used in its conventional sense to refer to a drug formulation that provides release of the drug in such a way as to produce pulsed plasma profiles of the drug after drug administration. The term “immediate release” is used in its conventional sense to refer to a drug formulation that provides for release of the drug immediately after drug administration.
The term “immediate release” is used in its conventional sense to refer to a drug formulation that provides for release of the drug immediately after drug administration.
By the term “transdermal” drug delivery is meant delivery by passage of a drug through the skin or mucosal tissue and into the bloodstream.
The term “topical administration” is used in its conventional sense to mean delivery of a topical drug or pharmacologically active agent to the skin or mucosa.
The term “oral administration” is used in its conventional sense to mean delivery of a drug through the mouth and ingestion through the stomach and digestive tract.
The term “inhalation administration” is used in its conventional sense to mean delivery of an aerosolized form of the drug by passage through the nose or mouth during inhalation and passage of the drug through the walls of the lungs.
The term “intravesical administration” is used in its conventional sense to mean delivery of a drug directly into the bladder.
By the term “parenteral” drug delivery is meant delivery by passage of a drug into the blood stream without first having to pass through the alimentary canal, or digestive tract. Parenteral drug delivery may be “subcutaneous,” referring to delivery of a drug by administration under the skin. Another form of parenteral drug delivery is “intramuscular,” referring to delivery of a drug by administration into muscle tissue. Another form of parenteral drug delivery is “intradermal,” referring to delivery of a drug by administration into the skin. An additional form of parenteral drug delivery is “intravenous,” referring to delivery of a drug by administration into a vein. An additional form of parenteral drug delivery is “intra-arterial,” referring to delivery of a drug by administration into an artery. Another form of parenteral drug delivery is “transdermal,” referring to delivery of a drug by passage of the drug through the skin and into the bloodstream. Another form of parenteral drug delivery is “intrathecal,” referring to delivery of a drug directly into the into the intrathecal space (where fluid flows around the spinal cord).
Still another form of parenteral drug delivery is “transmucosal,” referring to administration of a drug to the mucosal surface of an individual so that the drug passes through the mucosal tissue and into the individual's blood stream. Transmucosal drug delivery may be “buccal” or “transbuccal,” referring to delivery of a drug by passage through an individual's buccal mucosa and into the bloodstream. Another form of transmucosal drug delivery herein is “lingual” drug delivery, which refers to delivery of a drug by passage of a drug through an individual's lingual mucosa and into the bloodstream. Another form of transmucosal drug delivery herein is “sublingual” drug delivery, which refers to delivery of a drug by passage of a drug through an individual's sublingual mucosa and into the bloodstream. Another form of transmucosal drug delivery is “nasal” or “intranasal” drug delivery, referring to delivery of a drug through an individual's nasal mucosa and into the bloodstream. An additional form of transmucosal drug delivery herein is “rectal” or “transrectal” drug delivery, referring to delivery of a drug by passage of a drug through an individual's rectal mucosa and into the bloodstream. Another form of transmucosal drug delivery is “urethral” or “transurethral” delivery, referring to delivery of the drug into the urethra such that the drug contacts and passes through the wall of the urethra. An additional form of transmucosal drug delivery is “vaginal” or “transvaginal” delivery, referring to delivery of a drug by passage of a drug through an individual's vaginal mucosa and into the bloodstream. An additional form of transmucosal drug delivery is “perivaginal” delivery, referring to delivery of a drug through the vaginolabial tissue into the bloodstream.
In order to carry out the method of the invention, a selected active agent is administered to a patient suffering from pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. A therapeutically effective amount of the active agent may be administered orally, intravenously, subcutaneously, transmucosally (including buccally, sublingually, transurethrally, and rectally), topically, transdermally, by inhalation, intravesically, intrathecally or using any other route of administration.
Pain: Anatomical Basis and Proposed Mechanisms
The compositions and methods of the invention are useful for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. Pain is the perception of an aversive or unpleasant sensation and may arise through a variety of proposed mechanisms. These mechanisms include direct activation of specialized sensory receptors (nociceptors) that provide information about tissue damage (nociceptive pain), or by direct injury to nerves in the peripheral or central nervous system (neuropathic pain), often occurring in diseases such as diabetes, or as a result of trauma or a toxic dose of drugs (see, e.g., Basbaum and Jessell (2000) The Perception of Pain. In Principles of Neural Science, 4th. ed. pp. 472-491; Benevento et al. (2002) Physical Therapy Journal 82:601-12). Some pain syndromes are associated with overactivity of the sympathetic nervous system that occurs following peripheral nerve injury. The resulting pain and sympathetic activity is termed causalgia.
Nociceptors are the free nerve endings specifically designed to detect pain. There are three main classes of nociceptors: thermal, which are activated by extreme temperature; mechanical, which are activated by intense pressure; and polymodal, which are activated by a variety of mechanical, chemical or thermal stimuli. Nerve fibers can be classified into groups A (further divided into α, β, χ, or δ), B, or C, depending upon their size and whether or not they are myelinated. In general, pain sensations are carried by Aδ or C fibers. In some cases pain sensations may be transmitted by Aβ fibers. The thermal and mechanical nociceptors have small-diameter, thinly myelinated Aδ fibers, conducting signals at about 5-30 m/s, and are responsible for the sensation of fast, sharp pain. The polymodal nociceptors have small-diameter, nonmyelinated C fibers that conduct signals much more slowly, at speeds less than 1.0 m/s, leading to the perception of pain that is more prolonged, dull, or aching (Basbaum and Jessell (2000) The Perception of Pain. In Principles of Neural Science, 4th. Ed. pp. 472-491). In addition, silent nociceptors are present in the visceral organs. These receptors are not normally activated by noxious stimulation; however, inflammation and chemical insults may reduce the firing threshold of these receptors, potentially leading to secondary hyperalgesia and central sensitization (Basbaum and Jessell (2000) The Perception of Pain. In Principles of Neural Science, 4th. Ed. pp. 472-491).
Free nerve endings transfer pain signals via the peripheral nerve to the central nervous system where synapses are made on second order neurons, which then transmit the signal to the brain. This can occur in one of five ascending pathways: the spinothalamic, the spinoreticular, the spinomesencephalic, the cervicothalamic or the spinohypothalamic tract. The most prominent ascending pathway is the spinothalamic tract, in which the axons terminate in the thalamus. In the thalamus the second order neurons synapse on third order neurons in the ventral posterolateral (or posteromedial) nucleus which project to the cortex, where the pain is then processed with regard to localization and other characteristics such as intensity and quality.
Descending pathways also exist, which, when activated, inhibit the incoming pain signals, thereby suppressing pain transmission. These systems involve the periaqueductal grey, the dorsal raphe nuclei, locus ceruleus, and nuclei of the medullary reticular formation. Descending axons from the various nuclei run through the dorsolateral funiculus and synapse in the dorsal horn of the spinal cord.
In addition to these central connections, it has been theorized that other projections from the periphery may help to gate pain. The gate control theory of pain, for example, postulates that the large diameter sensory fibers inhibit incoming small diameter fiber signals, e.g., that pain transmission is inhibited with the activation of large diameter A afferents which are activated by vibration (R. Melzack & P. Wall, “Pain Mechanisms: A New Theory,” Science: 150, 171-179, 1965). This is the reason one shakes his or her hand when it is burned. It is also the basis for the use of transcutaneous electrical nerve stimulation (TENS) analgesia, a non-invasive procedure in which electrical impulses from an external stimulator unit are applied through electrodes placed on the skin to reduce the transmission of pain signals to the brain.
Chronic pelvic pain has been estimated to affect 15% of women. (J. Gunter, Obstet. Gynecol. Surv., 58: 615-23 (2003)). Chronic pelvic pain is a syndrome that results from a complex interaction between neurologic, musculoskeletal, and endocrine systems that is further influenced by behavioral and psychologic factors. Traditional treatments include surgical intervention, but such treatment has limited efficacy, with results attributed to placebo response. Many patients require a combination of both pharmacologic and nonpharmacologic treatments in addition to various types of invasive procedures. (J. Gunter, Obstet. Gynecol. Surv., 58: 615-23 (2003)).
Pain: Clinical Assessment
The sensation of pain is subjective. It has been theorized that concentrations of excitatory and inhibitory neurotransmitters in the spinal cord and the brain may vary from individual to individual in response to different stimuli, and may be part of the basis for differences in the tolerance for pain among individuals, and even in the same individual over time. In any event, the tolerance for or threshold of pain is a dynamic process that depends on the organism's state (e.g., minimal pain may be experienced in certain injuries suffered by soldiers in battle).
Diagnosis by the physician of the site and nature of the underlying pathology of pain depends almost entirely on historical information provided by the patient regarding its location, the extent that it tends to radiate, its intensity, whether it is continual or recurring, the conditions or medications which tend to reduce or increase its severity, and various other factors (“Pain Management: Pathophysiology of Pain and Pain Assessment” (2003) American Medical Association Continuing Medical Education Program). Information about the characteristics of a patient's pain is combined with information from neurological and physical examinations, and, if indicated, correlated with radiographic and laboratory evaluation to determine the cause of the pain and to suggest a treatment approach. However, the extent to which an underlying etiology for the pain should be sought depends on the context of the patient's illness. For example, laboratory and radiographic evaluation are usually appropriate in the case of acute pain and in cases of chronic pain that have: 1) not previously been adequately evaluated; 2) recently changed; or 3) are now occurring in association with an evolving disease (e.g., cancer) (“Pain Management: Pathophysiology of Pain and Pain Assessment” (2003) American Medical Association Continuing Medical Education Program).
Pain assessment is complicated by the fact that different patients may describe pain and its apparent sources in vastly different ways, or be virtually unable to describe it adequately as to specific site or nature. The prescription of proper treatment, of course, depends on an understanding of the underlying organic basis of the pain, and is particularly difficult with those patients who experience chronic pain syndromes. The distinction between acute and chronic or “persistent” pain is particularly relevant in the selection of effective analgesia, with acute pain characterized as recent onset with a relatively short duration, while chronic pain is usually characterized as persisting for more than 6 months. Quantifying the intensity of pain is also an essential part of initial and ongoing pain assessment, and a variety of validated pain scales are available to assist in the measurement of pain. Commonly used unidimensional scales include the Verbal Rating Scale (VRS), the Numeric Rating Scale (NRS), a Visual Analog Scale (VAS), and a Pictorial Scale (“Pain Management: Pathophysiology of Pain and Pain Assessment” (2003) American Medical Association Continuing Medical Education Program). Multidimensional pain scales include the McGill Pain Questionnaire (MPQ); and the Memorial Pain Assessment Card; the Brief Pain Inventory (BPI) (“Pain Management: Pathophysiology of Pain and Pain Assessment” (2003) American Medical Association Continuing Medical Education Program). Occasionally, a patient may require a special adjunctive assessment tool, meaning a validated tool developed to quantify the pain qualities specific to disorders (e.g., postherpetic neuralgia, complex regional pain syndrome, painful diabetic neuropathy), and such tools include the Neuropathic Pain Scale (“Pain Management: Pathophysiology of Pain and Pain Assessment” (2003) American Medical Association Continuing Medical Education Program).
Prostatitis and Prostadynia
Prostatitis and prostadynia are other lower urinary tract disorders that have been suggested to affect approximately 2-9% of the adult male population (Collins M M, et al., (1998) “How common is prostatitis? A national survey of physician visits,” Journal of Urology, 159: 1224-1228). Prostatitis is associated with an inflammation of the prostate, and may be subdivided into chronic bacterial prostatitis and chronic non-bacterial prostatitis. Chronic bacterial prostatitis is thought to arise from bacterial infection and is generally associated with such symptoms as inflammation of the prostate, the presence of white blood cells in prostatic fluid, and/or pain. Chronic non-bacterial prostatitis is an inflammatory and painful condition of unknown etiology characterized by excessive inflammatory cells in prostatic secretions despite a lack of documented urinary tract infections, and negative bacterial cultures of urine and prostatic secretions. Prostadynia (chronic pelvic pain syndrome) is a condition associated with the painful symptoms of chronic non-bacterial prostatitis without an inflammation of the prostate.
Currently, there are no established treatments for prostatitis and prostadynia. Antibiotics are often prescribed, but with little evidence of efficacy. COX-2 selective inhibitors and α-adrenergic blockers and have been suggested as treatments, but their efficacy has not been established. Hot sitz baths and anticholinergic drugs have also been employed to provide some symptomatic relief
Interstitial Cystitis
Interstitial cystitis is another lower urinary tract disorder of unknown etiology that predominantly affects young and middle-aged females, although men and children can also be affected. Symptoms of interstitial cystitis may include irritative voiding symptoms, urinary frequency, urgency, nocturia and suprapubic or pelvic pain related to and relieved by voiding. Many interstitial cystitis patients also experience headaches as well as gastrointestinal and skin problems. In some extreme cases, interstitial cystitis may also be associated with ulcers or scars of the bladder. Past treatments for interstitial cystitis have included the administration of antihistamines, sodium pentosanpolysulfate, dimethylsulfoxide, steroids, tricyclic antidepressants and narcotic antagonists, although these methods have generally been unsuccessful (Sant, G. R. (1989) Interstitial cystitis: pathophysiology, clinical evaluation and treatment. Urology Annal 3: 171-196).
Vulvodynia and Vulvar Vestibulitis
Vulvodynia and vulvar vestibulitis have been etiologically and pathologically linked to such lower urinary tract disorders as interstitial cystitis (See Selo-Ojeme et al. (2002) Int. Urogynecol. J Pelvic Floor Dysfunction 13: 261-2; Metts (2001) Am. Fam. Physician 64: 1199-206; Wesselmann (2001) World J. Urol. 19: 180-5; Parsons et al. (2001) Obstet. Gynecol. 98: 127-32; Heim (2001) Am. Fam. Physician 63: 1535-44; Stewart et al. (1997) J. Reprod. Med. 42: 131-4; Fitzpatrick et al. (1993) Obstet. Gynecol. 81: 860-2). Vulvar vestibulitis syndrome (herein “vulvar vestibulitis”) is a subtype of vulvodynia. Vulvodynia is a complex gynecologic syndrome characterized by unexplained vulvar pain, sexual dysfunction, and psychological disability. Although the exact prevalence of vulvodynia is unknown, the condition is relatively common. It has been estimated that 1.5 million American women may suffer from some degree of vulvodynia.
The most common subtype of vulvodynia is vulvar vestibulitis (also called “focal vulvitis” and “vestibular adenitis”). Vulvar vestibulitis presents a constellation of symptoms involving and limited to the vulvar vestibule. The criteria for recognizing vulvar vestibulitis include: 1) pain on vestibular touch or attempted vaginal entry; 2) tenderness to Q-tip pressure localized within the vulvar vestibule; 3) physical findings confined to vestibular erythema of various degrees; and 4) an exclusion of other causes for vestibular erythema and tenderness, such as candidiasis (yeast infections) or herpes infections. Other symptoms include itching, swelling and excoriation.
The pain in vulvar vestibulitis may be described as sharp, burning, or a sensation of rawness. In severe cases, dyspareunia (recurrent or persistent genital pain associated with sexual intercourse) totally prohibits sexual intercourse. Pain may also be elicited on tampon insertion, biking, or wearing tight pants. The erythema may be diffuse or focal, and may be localized around the orifices of the vestibular glands or at the fourchette. In addition, patient symptoms may often include itching. Morbidities extend well beyond the local symptoms, with many women undergoing tremendous changes in psychosexual self-image, and can include profound adverse effects on marriages and other important relationships.
Vulvar vestibulitis may be acute or chronic. In one study, an arbitrary cutoff of three months of symptoms was used to distinguish between the acute and chronic forms (Marinoff and Turner, Am. J. Obstet. Gynecol. 165:1228-33, 1991). Most clinicians use an arbitrary cutoff of six months to distinguish between the acute and chronic forms. Some investigators have attempted to find a common histopathological aspect to vulvar vestibulitis, but have failed to do so (Pyka et al. (1988) Int. J. Gynecol. Pathol. 7: 249-57).
The causes of vulvar vestibulitis are multifactorial. Known and suspected causes of the acute form include fungal or bacterial infection (e.g. Candida, Trichomonas), chemical irritants (e.g. soaps, douches, sprays), therapeutic agents (e.g. antiseptics, suppositories, creams, 5-fluorouracil methods (e.g. cryosurgery, laser treatment), and allergic drug reactions. In the acute form, treatment of the presumed cause may lead to rapid relief.
Vulvar vestibulitis may become chronic if the cause becomes persistent or recurrent and may persist long after all suspected causes have been treated. Many causes of chronic vulvar vestibulitis are of unknown etiology. Although no direct cause and effect relationship has been shown, it has been suggested that oxalates in the urine, altered vaginal pH, localized peripheral neuropathy, and subclinical viral infections can all contribute to the syndrome. A history of fungal infection is present in most patients who have vulvar vestibulitis, suggesting that recurrent yeast infections may somehow play a role in the initiation of the syndrome. It has been suggested that conditions such as recurrent candidiasis may lead to local changes in the vaginal immune system, including both Th1 and Th2 type responses (Fidel and Sobel, Clin. Microbiol. Reviews 9(3):335-48, 1996).
Because of its multiple causes, and its frequently unknown causes, vulvar vestibulitis can be very difficult to treat. The first-line therapy for vulvar vestibulitis is the treatment of its suspected causes. This includes the pharmacologic treatment of infections and the discontinued use of the irritants and therapeutic agents, local and systemic, that may contribute to the problem. Topical anesthetics, corticosteroids, and sex hormones may provide some symptomatic relief. Further treatments may include dietary modifications, physical therapy and biofeedback, use of topical, oral, or injected therapeutic agents, or surgery. Unfortunately, no single treatment works in all patients. Moreover, many of these approaches involve complex medical procedures, significant costs, and/or undesirable side effects.
Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is a biopsychosocial disorder with variable symptoms wherein a disturbance in the interaction between intestinal motility and sensation, the brain, and the autonomic nervous system produces the syndrome. IBS is characterized by a group of symptoms where abdominal pain or discomfort is associated with a change in bowel pattern, such as loose stool, more frequent bowel movements, diarrhea, and/or constipation, in the absence of demonstrable organic pathology.
As IBS presents no specific motility or structural correlates, it remains a clinically defined illness defined by either the Manning or Rome II Criteria. The Manning criteria were originally established in 1978 to distinguish IBS from organic bowel disease (Manning A P, Thompson W G, Heaton K W, Morris A F. Towards a positive diagnosis of the irritable bowel. Br. Med. J. 1978; 2:653-4). The criteria are:
1. Onset of pain associated with more frequent bowel movements
2. Onset of pain associated with looser bowel movements
3. Pain relieved by defecation
4. Visible abdominal bloating
5. Subjective sensation of incomplete evacuation more than 25% of the time
6. Mucorrhea more than 25% of the time
The Rome II criteria for IBS include reports for at least 12 weeks in the preceding 12 months, which need not be consecutive, of abdominal pain or discomfort that has two of three features:
Subjects with IBS exhibit visceral hypersensitivity, the presence of which behavioral studies have shown is the most consistent abnormality in IBS. For example, patients and controls were evaluated for their pain thresholds in response to progressive distension of the sigmoid colon induced by a balloon. At the same volume of distension, the patients reported higher pain scores compared to controls. This finding has been reproduced in many studies and with the introduction of the barostat, a computerized distension device, the distension procedures have been standardized. Two concepts of visceral hypersensitivity, hyperalgesia and allodynia, have been introduced. More specifically, hyperalgesia refers to the situation in which normal visceral sensations are experienced at lower intraluminal volumes. While for a finding of allodynia, pain or discomfort is experienced at volumes usually producing normal internal sensations (see, for example, Mayer E. A. and Gebhart, G. F., Basic and Clinical Aspects of Chronic Abdominal Pain, Vol 9, 1 ed. Amsterdam: Elsevier, 1993:3-28).
As such, IBS is a functional bowel disorder in which abdominal pain or discomfort is associated with defecation or a change in bowel habit. Therefore, IBS has elements of an intestinal motility disorder, a visceral sensation disorder, and a central nervous disorder. While the symptoms of IBS have a physiological basis, no physiological mechanism unique to IBS has been identified. In some cases, the same mechanisms that cause occasional abdominal discomfort in healthy individuals operate to produce the symptoms of IBS. The symptoms of IBS are therefore a product of quantitative differences in the motor reactivity of the intestinal tract, and increased sensitivity to stimuli or spontaneous contractions.
In addition to the above diagnosis tools, IBS patients can be categorized according to symptoms and severity. Chronic diarrhea which is associated with abdominal pain and which is not attributable to an organic cause is referred to as “irritable bowel syndrome with a diarrhea predominance” or diarrhea predominant IBS (Hasler et al., 1995, In: Textbook of Gastroenterology, 2nd ed., Yamada, Ed., J. B. Lippincott Co., Philadelphia, pp. 1832-1855). Patients exhibit diarrhea predominant IBS if their usual bowel movement frequency is more than three times per day, or if their ususal form of stool is loose and not hard, or if they frequently feel the sense of urgency and do not strain at the stools. Patients exhibit constipation predominant IBS if their usual bowel movement frequency is less than three times per week, or if their usual form of stool is hard and not loose, or if they often strain at the stools and do not frequently feel the sense of urgency. Patient not described as exhibiting diarrhea predominant IBS or constipation predominant IBS can be termed as exhibiting non-specific or alternating constipation/diarrhea IBS.
Functional Abdominal Pain Syndrome
Functional Abdominal Pain Syndrome (FAPS) is also known as chronic idiopathic abdominal pain or chronic functional abdominal pain. These terms are generally used to describe pain for at least six months that is poorly related to bowel function and is associated with some loss of daily activities. Diagnostic criteria for FAPS include at least six months of: (1) continuous or nearly continuous abdominal pain; and (2) no or only occasional relation of pain with physiological events (e.g. eating, defecation, menses); and (3) some loss of daily functioning; and (4) the pain is not feigned; and (5) insufficient criteria exists for diagnosing other functional gastrointestinal disorders that would explain the abdominal pain.
Functional Dyspepsia
Functional dyspepsia is a functional bowel disorder in which chronic or recurrent symptoms are centered in the upper abdomen without presence of other known disease, such as infection, inflammation, or ulcer. Symptoms include pain and discomfort, which is meant to represent other symptoms, such as early satiety, nausea, vomiting, or bloating. There are two primary motor dysfunctions that can be described in relation to functional dyspepsia. First, more than 30% of adults with functional dyspepsia (or non-ulcer dyspepsia) have impaired gastric emptying. Second, impaired gastric accommodation is also frequent.
Other Diseases or Disorders Associated With Pain
Other diseases or disorders associated with pain that may be treated by compositions of the present invention include, but are not limited to, inflammatory disorders, such as rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, psoriasis, chondrocalcinosis, gout, inflammatory bowel disease, ulcerative colitis, Crohn's disease and cachexia; renal cholic; diabetic complications; noninflammatory cartilage damage; cancer; allodynia; peripheral nerve trauma; herpes virus infection; diabetes mellitus; causalgia; neuroma; limb amputation; vasculitis; nerve damage from chronic alcoholism, human immunodeficiency virus infection, hypothyroidism, uremia, or vitamin deficiencies; trigeminal neuralgia; diabetic neuropathy; restless leg syndrome; acute herpetic and postherpetic neuralgia; brachial plexus avulsion; occipital neuralgia; phantom limb; burn; other forms of neuralgia; neuropathic and idiopathic pain syndrome; head trauma; spinal cord trauma; injury from general anoxia, hypoxia, hypoglycemia, or hypotension as well as similar injuries seen during procedures from embole, hyperfusion, and hypoxia; pain during cardiac bypass surgery; incidents of intracranial hemorrhage; perinatal asphyxia; cardiac arrest; status epilepticus; irritable bowel syndrome; osteoarthritis; neuropathological disorders; visceral pain; functional bowel disorders; dysmenorrhea; pelvic pain; cystitis; pancreatitis; postoperative pain, such as following a dental extraction; migraine; headache; sero-negative (non-rheumatoid) arthropathies; non-articular rheumatism; dyspepsia; gastritis; peptic ulcer; lower gastrointestinal bleeding and perforation; ileitis; and peri-articular disorders. Still further examples of diseases or disorders associated with pain include those as described in U.S. Pat. Nos. 6,689,906; 6,680,343; 6,635,673; 6,642,398; 6,593,368; 6,489,352; 6,451,857; 6,436,974; 6,426,368; 6,359,005; 6,329,429; 6,326,374; 6,316,638; 6,306,910; 6,245,801; 6,242,488; 6,153,650; 6,127,418; 6,103,932; 6,020,370; 6,001,876; 5,929,088; 6,706,723; 6,627,771; 6,544,998; 6,620,829; and 6,596,900.
Peripheral vs. Central Effects
The mammalian nervous system comprises a central nervous system (CNS, comprising the brain and spinal cord) and a peripheral nervous system (PNS, comprising sympathetic, parasympathetic, sensory, motor, and enteric neurons outside of the brain and spinal cord). Where an active agent according to the present invention is intended to act centrally (i.e., exert its effects via action on neurons in the CNS), the active agent must either be administered directly into the CNS or be capable of bypassing or crossing the blood-brain barrier. The blood-brain barrier is a capillary wall structure that effectively screens out all but selected categories of substances present in the blood, preventing their passage into the CNS. The unique morphologic characteristics of the brain capillaries that make up the blood-brain barrier are: 1) epithelial-like high resistance tight junctions which literally cement all endothelia of brain capillaries together within the blood-brain barrier regions of the CNS; and 2) scanty pinocytosis or transendothelial channels, which are abundant in endothelia of peripheral organs. Due to the unique characteristics of the blood-brain barrier, hydrophilic drugs and peptides that readily gain access to other tissues in the body are barred from entry into the brain or their rates of entry are very low.
The blood-brain barrier can be bypassed effectively by direct infusion of the active agent into the central nervous system, or by intranasal administration or inhalation of formulations suitable for uptake and retrograde transport of the active agent by olfactory neurons. The most common procedure for administration directly into the CNS is the implantation of a catheter into the ventricular system or intrathecal space. Alternatively, the active agent can be modified to enhance its transport across the blood-brain barrier. This generally requires some solubility of the drug in lipids, or other appropriate modification known to one of skill in the art. For example, the active agent may be truncated, derivatized, latentiated (converted from a hydrophilic drug into a lipid-soluble drug), conjugated to a lipophilic moiety or to a substance that is actively transported across the blood-brain barrier, or modified using standard means known to those skilled in the art. See, for example, Pardridge, Endocrine Reviews 7: 314-330 (1986) and U.S. Pat. No. 4,801,575.
Where an active agent according to the present invention is intended to act exclusively peripherally (i.e., exert its effects via action either on neurons in the PNS or directly on target tissues), it may be desirable to modify the compounds of the present invention such that they will not pass the blood-brain barrier. The principle of blood-brain barrier permeability can therefore be used to design active agents with selective potency for peripheral targets. Generally, a lipid-insoluble drug will not cross the blood-brain barrier, and will not produce effects on the CNS. A basic drug that acts on the nervous system may be altered to produce a selective peripheral effect by quaternization of the drug, which decreases its lipid solubility and makes it virtually unavailable for transfer to the CNS. For example, the charged antimuscarinic drug methscopalamine bromide has peripheral effects while the uncharged antimuscarinic drug scopolamine acts centrally. One of skill in the art can select and modify active agents of the present invention using well-known standard chemical synthetic techniques to add a lipid impermeable functional group such a quaternary amine, sulfate, carboxylate, phosphate, or sulfonium to prevent transport across the blood-brain barrier. Such modifications are by no means the only way in which active agents of the present invention may be modified to be impermeable to the blood-brain barrier; other well known pharmaceutical techniques exist and would be considered to fall within the scope of the present invention.
Agents
Compounds useful in the present invention include any active agent as defined elsewhere herein. Such active agents include, for example, α2δ subunit calcium channel modulators, including GABA analogs (e.g. gabapentin and pregabalin), as described elsewhere herein, as well as smooth muscle modulators, including antimuscarinics, α3 adrenergic agonists, spasmolytics, neurokinin receptor antagonists, bradykinin receptor antagonists, and nitric oxide donors, as described elsewhere herein.
Voltage gated calcium channels, also known as voltage dependent calcium channels, are multi-subunit membrane-spanning proteins which permit controlled calcium influx from an extracellular environment into the interior of a cell. Opening and closing (gating) of voltage gated calcium channels is controlled by a voltage sensitive region of the protein containing charged amino acids that move within an electric field. The movement of these charged groups leads to conformational changes in the structure of the channel resulting in conducting (open/activated) or non-conducting (closed/inactivated) states.
Voltage gated calcium channels are present in a variety of tissues and are implicated in several vital processes in animals. Changes in calcium influx into cells mediated through these calcium channels have been implicated in various human diseases such as epilepsy, stroke, brain trauma, Alzheimer's disease, multi-infarct dementia, other classes of dementia, Korsakoff's disease, neuropathy caused by a viral infection of the brain or spinal cord (e.g., human immunodeficiency viruses, etc.), amyotrophic lateral sclerosis, convulsions, seizures, Huntington's disease, amnesia, or damage to the nervous system resulting from reduced oxygen supply, poison, or other toxic substances (See, e.g., U.S. Pat. No. 5,312,928).
Voltage gated calcium channels have been classified by their electrophysiological and pharmacological properties as T, L, N, P and Q types (for reviews see McCleskey et al. (1991) Curr. Topics Membr. 39:295-326; and Dunlap et al. (1995) Trends. Neurosci. 18:89-98). Because there is some overlap in the biophysical properties of the high voltage-activated channels, pharmacological profiles are useful to further distinguish them. L-type channels are sensitive to dihydropyridine agonists and antagonists. N-type channels are blocked by the peptides ω-conotoxin GVIA and ω-conotoxin MVIIA, peptide toxins from the cone shell mollusks, Conus geographus and Conus magus, respectively. P-type channels are blocked by the peptide ω-agatoxin IVA from the venom of the funnel web spider, Agelenopsis aperta, although some studies have suggested that ω-agatoxin IVA also blocks N-type channels (Sidach at al. (2000) J. Neurosci. 20: 7174-82). A fourth type of high voltage-activated calcium channel (Q-type) has been described, although whether the Q- and P-type channels are distinct molecular entities is controversial (Sather et al. (1995) Neuron 11:291-303; Stea et al. (1994) Proc. Natl. Acad. Sci. USA 91:10576-10580; Bourinet et al. (1999) Nature Neuroscience 2:407-415).
Voltage gated calcium channels are primarily defined by the combination of different subunits: α1, α2, β, γ, and δ (see Caterall (2000) Annu. Rev. Cell. Dev. Biol. 16: 521-55). Ten types of α1 subunits, four complexes, four β subunits, and two γ subunits are known (see Caterall, Annu. Rev. Cell. Dev. Biol., supra; see also Klugbauer et al. (1999) J. Neurosci. 19: 684-691).
Based upon the combination of different subunits, calcium channels may be divided into three structurally and functionally related families: Cav1, Cav2, and Cav3 (for reviews, see Caterall, Annu. Rev. Cell. Dev. Biol., supra; Ertel et al. (2000) Neuron 25: 533-55). L-type currents are mediated by a Cav1 family of α1 subunits (see Caterall, Annu. Rev. Cell. Dev. Biol., supra). Cav2 channels form a distinct family with less than 40% amino acid sequence identity with Cav1α1 subunits (see Caterall, Annu. Rev. Cell. Dev. Biol., supra). Cloned Cav2.1 subunits conduct P- or Q-type currents that are inhibited by co-agatoxin IVA (see Caterall, Annu. Rev. Cell. Dev. Biol., supra; Sather et al. (1993) Neuron 11: 291-303; Stea et al. (1994) Proc. Natl. Acad. Sci. USA 91: 10576-80; Bourinet et al. (1999) Nat. Neurosci. 2: 407-15). Cav2.2 subunits conduct N-type calcium currents and have a high affinity for ω-conotoxin GVIA, ω-conotoxin MVIIA, and synthetic versions of these peptides including Ziconotide (see Caterall, Annu. Rev. Cell. Dev. Biol., supra; Dubel et al. (1992) Proc. Natl. Acad. Sci. USA 89:5058-62; Williams et al. (1992) Science 257: 389-95). Cloned Cav2.3 subunits conduct a calcium current known as R-type and are resistant to organic antagonists specific for L-type calcium currents and peptide toxins specific for N-type or P/Q-type currents (see Caterall, Annu. Rev. Cell. Dev. Biol., supra; Randall et al. (1995) J. Neurosci. 15: 2995-3012; Soong et al. (1994) Science 260: 1133-36; Zhang et al. (1993) Neuropharmacology 32: 1075-88).
Gamma-aminobutyric acid (GABA) analogs are compounds that are derived from or based on GABA. GABA analogs are either readily available or readily synthesized using methodologies known to those of skill in the art. Exemplary GABA analogs include gabapentin and pregabalin.
Gabapentin (Neurontin, or 1-(aminomethyl) cyclohexaneacetic acid) is an anticonvulsant drug with a high binding affinity for some calcium channel subunits, and is represented by the following structure:
Gabapentin is one of a series of compounds of formula:
in which R1 is hydrogen or a lower alkyl radical and n is 4, 5, or 6. Although gabapentin was originally developed as a GABA-mimetic compound to treat spasticity, gabapentin has no direct GABAergic action and does not block GABA uptake or metabolism. (For review, see Rose et al. (2002) Analgesia 57:451-462). Gabapentin has been found, however, to be an effective treatment for the prevention of partial seizures in patients who are refractory to other anticonvulsant agents (Chadwick (1991) Gabapentin, In Pedley T A, Meldrum B S (eds.), Recent Advances in Epilepsy, Churchill Livingstone, N.Y., pp. 211-222). Gabapentin and the related drug pregabalin may interact with the α2δ subunit of calcium channels (Gee et al. (1996) J. Biol. Chem. 271: 5768-5776).
In addition to its known anticonvulsant effects, gabapentin has been shown to block the tonic phase of nociception induced by formalin and carrageenan, and exerts an inhibitory effect in neuropathic pain models of mechanical hyperalgesia and mechanical/thermal allodynia (Rose et al. (2002) Analgesia 57: 451-462). Double-blind, placebo-controlled trials have indicated that gabapentin is an effective treatment for painful symptoms associated with diabetic peripheral neuropathy, post-herpetic neuralgia, and neuropathic pain (see, e.g., Backonja et al. (1998) JAMA 280:1831-1836; Mellegers et al. (2001) Clin. J Pain 17:284-95).
Pregabalin, (S)-(3-aminomethyl)-5-methylhexanoic acid or (S)-isobutyl GABA, is another GABA analog whose use as an anticonvulsant has been explored (Bryans et al. (1998) J. Med. Chem. 41:1838-1845). Pregabalin has been shown to possess even higher binding affinity for the α2δ subunit of calcium channels than gabapentin (Bryans et al. (1999) Med. Res. Rev. 19:149-177).
Exemplary GABA analogs and fused bicyclic or tricyclic amino acid analogs of gabapentin that are useful in the present invention include:
Other agents useful in the present invention include any compound that binds to the α2δ subunit of a calcium channel. GABA analogs which display binding affinity to the α2δ subunit of calcium channels and that are therefore useful in the present invention include, without limitation, cis-(1S,3R)-(1-(aminomethyl)-3-methylcyclohexane)acetic acid, cis-(1R,3S)-(1-(aminomethyl)-3-methylcyclohexane)acetic acid, 1α,3α,5α-(1-aminomethyl)-(3,5-dimethylcyclohexane)acetic acid, (9-(aminomethyl)bicyclo[3.3.1]non-9-yl)acetic acid, and (7-(aminomethyl)bicyclo[2.2.1]hept-7-yl)acetic acid (Bryans et al. (1998) J. Med. Chem. 41:1838-1845; Bryans et al. (1999) Med. Res. Rev. 19:149-177). Other compounds that have been identified as modulators of calcium channels include, but are not limited to those described in U.S. Pat. No. 6,316,638, U.S. Pat. No. 6,492,375, U.S. Pat. No. 6,294,533, U.S. Pat. No. 6,011,035, U.S. Pat. No. 6,387,897, U.S. Pat. No. 6,310,059, U.S. Pat. No. 6,294,533, U.S. Pat. No. 6,267,945, PCT Publication No. WO01/49670, PCT Publication No. WO001/46166, and PCT Publication No. WO01/45709. The identification of which of these compounds have a binding affinity for the α2δ subunit of calcium channels can be determined by performing α2δ binding affinity studies as described by Gee et al. (Gee et al. (1996) J. Biol. Chem. 271:5768-5776). The identification of still further compounds, including other GABA analogs, that exhibit binding affinity for the α2δ subunit of calcium channels can also be determined by performing α2δ binding affinity studies as described by Gee et al. (Gee et al. (1996) J. Biol. Chem. 271:5768-5776).
Furthermore, compositions and formulations encompassing GABA analogs and cyclic amino acid analogs of gabapentin and that would be useful in the present invention include compositions disclosed in PCT Publication No. WO 99/08670, U.S. Pat. No. 6,342,529, controlled release formulations as disclosed in U.S. Application No. 20020119197 and U.S. Pat. No. 5,955,103, and sustained release compounds and formulations as disclosed in PCT Publication No. WO 02/28411, PCT Publication No. WO 02/28881, PCT Publication No. WO 02/28883, PCT Publication No. WO 02/32376, PCT Publication No. WO 02/42414, U.S. Application No. 20020107208, U.S. Application No. 20020151529, and U.S. Application No. 20020098999.
Acetylcholine is a chemical neurotransmitter in the nervous systems of all animals; “Cholinergic neurotransmission” refers to neurotransmission that involves acetylcholine, and has been implicated in the control of functions as diverse as locomotion, digestion, cardiac rate, “fight or flight” responses, and learning and memory (Salvaterra (February 2000) Acetylcholine. In Encyclopedia of Life Sciences. London: Nature Publishing Group, http:/www.els.net). Receptors for acetylcholine are classified into two general categories based on the plant alkaloids that preferentially interact with them: 1) nicotinic (nicotine binding); or 2) muscarinic (muscarine binding) (See, e.g., Salvaterra, Acetylcholine, supra).
The two general categories of acetylcholine receptors may be further divided into subclasses based upon differences in their pharmacological and electrophysiological properties. For example, nicotinic receptors are composed of a variety of subunits that are used to identify the following subclasses: 1) muscle nicotinic acetylcholine receptors; 2) neuronal nicotinic acetylcholine receptors that do not bind the snake venom α-bungarotoxin; and 3) neuronal nicotinic acetylcholine receptors that do bind the snake venom α-bungarotoxin (Dani et al. (July 1999) Nicotinic Acetylcholine Receptors in Neurons. In Encyclopedia of Life Sciences. London: Nature Publishing Group, http:/www.els.net; Lindstrom (October 2001) Nicotinic Acetylcholine Receptors. In Encyclopedia of Life Sciences. London: Nature Publishing Group, http:/www.els.net). By contrast, muscarinic receptors may be divided into five subclasses, labeled M1-M5, and preferentially couple with specific G-proteins (M1, M3, and M5 with Gq; M2 and M4 with Gi/G0) (Nathanson (July 1999) Muscarinic Acetylcholine Receptors. In Encyclopedia of life Sciences. London: Nature Publishing Group, http:/www.els.net). In general, muscarinic receptors have been implicated in bladder function (See, e.g., Appell (2002) Cleve. Clin. J. Med. 69: 761-9; Diouf et al. (2002) Bioorg. Med. Chem. Lett. 12: 2535-9; Crandall (2001) J. Womens Health Gend. Based Med. 10: 735-43; Chapple (2000) Urology 55: 33-46).
Other agents useful in the present invention include any anticholinergic agent, specifically, any antimuscarinic agent. Particularly useful in the methods of the present invention is oxybutynin, also known as 4-diethylaminio-2-butynyl phenylcyclohexyglycolate. It has the following structure:
Ditropan® (oxybutynin chloride) is the d,l racemic mixture of the above compound, which is known to exert antispasmodic effect on smooth muscle and inhibit the muscarinic action of acetylcholine on smooth muscle. Metabolites and isomers of oxybutynin have also been shown to have activity useful according to the present invention. Examples include, but are not limited to N-desethyl-oxybutynin and S-oxybutynin (see, e.g., U.S. Pat. Nos. 5,736,577 and 5,532,278).
Additional compounds that have been identified as antimuscarinic agents and are useful in the present invention include, but are not limited to:
The identification of further compounds that have antimuscarinic activity and would therefore be useful in the present invention can be determined by performing muscarinic receptor binding specificity studies as described by Nilvebrant (2002) Pharmacol. Toxicol. 90: 260-7 or cystometry studies as described by Modiri et al. (2002) Urology 59: 963-8.
Adrenergic receptors are cell-surface receptors for two major catecholamine hormones and neurotransmitters: noradrenaline and adrenaline. (Malbon et al. (February 2000) Adrenergic Receptors. In Encyclopedia of Life Sciences. London: Nature Publishing Group, http:/www.els.net). Adrenergic receptors have been implicated in critical physiological processes, including blood pressure control, myocardial and smooth muscle contractility, pulmonary function, metabolism, and central nervous system activity (See, e.g., Malbon et al., Adrenergic Receptors, supra). Two classes of adrenergic receptors have been identified, α and β, that may be further subdivided into three major families (α1, α2, and β), each with at least three subtypes (α1A, B, and, D; α2A, B, and C; and β1, β2, and β3) based upon their binding characteristics to different agonists and molecular cloning techniques. (See, e.g., Malbon et al., drenergic Receptors, supra). It has been shown that β3 adrenergic receptors are expressed in the detrusor muscle, and that the detrusor muscle relaxes with a β3-agonist (Takeda, M. et al. (1999) J. Pharmacol. Exp. Ther. 288:1367-1373), and in general, β3 adrenergic receptors have been implicated in bladder function (See, e.g., Takeda et al. (2002) Neuourol. Urodyn. 21: 558-65; Takeda et al. (2000) J. Pharmacol Exp. Ther. 293: 939-45.
Other agents useful in the present invention include any β3 adrenergic agonist agent. Compounds that have been identified as β3 adrenergic agonist agents and are useful in the present invention include, but are not limited to:
Spasmolytics are compounds that relieve or prevent muscle spasms, especially of smooth muscle. In general, spasmolytics have been implicated as having efficacy in the treatment of bladder disorders (See. e.g., Takeda et al. (2000) J. Pharmacol. Exp. Ther. 293: 939-45).
Other agents useful in the present invention include any spasmolytic agent. Compounds that have been identified as spasmolytic agents and are useful in the present invention include, but are not limited to:
Tachykinins (TKs) are a family of structurally related peptides that include substance P, neurokinin A (NKA) and neurokinin B (NKB). Neurons are the major source of TKs in the periphery. An important general effect of TKs is neuronal stimulation, but other effects include endothelium-dependent vasodilation, plasma protein extravasation, mast cell recruitment and degranulation and stimulation of inflammatory cells (See Maggi, C. A. (1991) Gen. Pharmacol., 22: 1-24). In general, tachykinin receptors have been implicated in bladder function (See, e.g., Kamo et al. (2000) Eur. J. Pharmacol. 401: 235-40 and Omhura et al. (1997) Urol. Int. 59: 221-5).
Substance P activates the neurokinin receptor subtype referred to as NK1. Substance P is an undecapeptide that is present in sensory nerve terminals. Substance P is known to have multiple actions that produce inflammation and pain in the periphery after C-fiber activation, including vasodilation, plasma extravasation and degranulation of mast cells (Levine, J. D. et. al. (1993) J. Neurosci. 13: 2273).
Neurokinin A is a peptide which is colocalized in sensory neurons with substance P and which also promotes inflammation and pain. Neurokinin A activates the specific neurokinin receptor referred to as NK2 (Edmonds-Alt, S., et. al. (1992) Life Sci. 50: PL101). In the urinary tract, TKs are powerful spasmogens acting through only the NK2 receptor in the human bladder, as well as the human urethra and ureter (Maggi, C. A. (1991) Gen. Pharmacol., 22:1-24).
Other agents useful in the present invention include any neurokinin receptor antagonist agent. Suitable neurokinin receptor antagonists for use in the present invention that act on the NK1 receptor include, but are not limited to: 1-imino-2-(2-methoxy-phenyl)-ethyl)-7,7-diphenyl-4-perhydroisoindolone(3aR,7aR) (“RP 67580”); 2S,3S-cis-3-(2-methoxybenzylamino)-2-benzhydrylquinuclidine (“CP 96,345”); and (aR,9R)-7-[3,5-bis(trifluoromethyl)benzyl]-8,9,10,11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4]diazocino[2,1-g][1,7]naphthyridine-6,13-dione)(“TAK-637”). Suitable neurokinin receptor antagonists for use in the present invention that act on the NK2 receptor include but are not limited to: ((S)-N-methyl-N-4-(4-acetylamino-4-phenylpiperidino)-2-(3,4-dichloropheny 1)butylbenzamide (“SR 48968”); Met-Asp-Trp-Phe-Dap-Leu (“MEN 10,627”); and cyc(Gln-Trp-Phe-Gly-Leu-Met) (“L 659,877”). Suitable neurokinin receptor antagonists for use in the present invention also include acids, salts, esters, amides, prodrugs, active metabolites, and other derivatives of any of the agents mentioned above. The identification of further compounds that have neurokinin receptor antagonist activity and would therefore be useful in the present invention can be determined by performing binding assay studies as described in Hopkins et al. (1991) Biochem. Biophys. Res. Comm. 180: 1110-1117; and Aharony et al. (1994) Mol. Pharmacol. 45: 9-19.
Bradykinin receptors generally are divided into bradykinin1 (B1) and bradykinin2 (B2) subtypes. Studies have shown that acute peripheral pain and inflammation produced by bradykinin are mediated by the B2 subtype whereas bradykinin-induced pain in the setting of chronic inflammation is mediated via the B1 subtype (Perkins, M. N., et. al. (1993) Pain 53: 191-97); Dray, A., et. al. (1993) Trends Neurosci. 16: 99-104). In general, bradykinin receptors have been implicated in bladder function (See, e.g., Meini et al. (2000) Eur. J. Pharmacol. 388: 177-82 and Belichard et al. (1999) Br. J. Pharmacol. 128: 213-9).
Other agents useful in the present invention include any bradykinin receptor antagonist agent. Suitable bradykinin receptor antagonists for use in the present invention that act on the B1 receptor include but are not limited to: des-arg10HOE 140 (available from Hoechst Pharmaceuticals) and des-Arg9bradykinin (DABK). Suitable bradykinin receptor antagonists for use in the present invention that act on the B2 receptor include but are not limited to: D-Phe7-BK; D-Arg-(Hyp3-Thi5,8-D-Phe7)-BK (“NPC 349”); D-Arg-(Hyp3-D-Phe7)-BK (“NPC 567”); D-Arg-(Hyp3-Thi5-D-Tic7-Oic8)-BK (“HOE 140”); H-DArg-Arg-Pro-Hyp-Gly-Thi-c(Dab-DTic-Oic-Arg)c(7gamma-10alpha)(“MEN11270”); H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-DTic-Oic-Arg-OH(“Icatibant”); (E)-3-(6-acetamido-3-pyridyl)-N-[N-[2,4-dichloro-3-[(2-methyl-8-quinolinyl) oxymethyl]phenyl]-N-methylaminocarbonylmethyl]acrylamide (“FR173567”); and WIN 64338. These compounds are more fully described in Perkins, M. N., et. al., Pain, supra; Dray, A., et. al., Trends Neurosci., supra; and Meini et al. (2000) Eur. J. Pharmacol. 388: 177-82. Suitable neurokinin receptor antagonists for use in the present invention also include acids, salts, esters, amides, prodrugs, active metabolites, and other derivatives of any of the agents mentioned above. The identification of further compounds that have bradykinin receptor antagonist activity and would therefore be useful in the present invention can be determined by performing binding assay studies as described in Manning et al. (1986) J. Pharmacol. Exp. Ther. 237: 504 and U.S. Pat. No. 5,686,565.
Nitric oxide donors may be included in the present invention particularly for their anti-spasm activity. Nitric oxide (NO) plays a critical role as a molecular mediator of many physiological processes, including vasodilation and regulation of normal vascular tone. The action of NO is implicated in intrinsic local vasodilation mechanisms. NO is the smallest biologically active molecule known and is the mediator of an extraordinary range of physiological processes (Nathan (1994) Cell 78: 915-918; Thomas (1997) Neurosurg. Focus 3: Article 3). NO is also a known physiologic antagonist of endothelin-1, which is the most potent known mammalian vasoconstrictor, having at least ten times the vasoconstrictor potency of angiotensin II (Yanagisawa et al. (1988) Nature 332: 411-415; Kasuya et al. (1993) J. Neurosurg. 79: 892-898; Kobayashi et al., (1991) Neurosurgery 28: 673-679). The biological half-life of NO is extremely short (Morris et al. (1994) Am. J. Physiol. 266: E829-E839; Nathan (1994) Cell 78: 915-918). NO accounts entirely for the biological effects of endothelium-derived relaxing factor (EDRF) and is an extremely potent vasodilator that is believed to work through the action of cGMP-dependent protein kinases to effect vasodilation (Henry et al. (1993) FASEB J. 7: 1124-1134; Nathan (1992) FASEB J. 6: 3051-3064; Palmer et al., (1987) Nature 327: 524-526; Snyder et al. (1992) Scientific American 266: 68-77).
Within endothelial cells, an enzyme known as NO synthase (NOS) catalyzes the conversion of L-arginine to NO which acts as a diffusible second messenger and mediates responses in adjacent smooth muscle cells. NO is continuously formed and released by the vascular endothelium under basal conditions which inhibits contractions and controls basal coronary tone and is produced in the endothelium in response to various agonists (such as acetylcholine) and other endothelium dependent vasodilators. Thus, regulation of NOS activity and the resultant levels of NO are key molecular targets controlling vascular tone (Muramatsu et. al. (1994) Coron. Artery Dis. 5:815-820).
Other agents useful in the present invention include any nitric oxide donor agent. Suitable nitric oxide donors for the practice of the present invention include but are not limited to:
Many organic compounds exist in optically active forms, i.e., they have the ability to rotate the plane of plane-polarized light. In describing an optically active compound the prefixes R and S are used to denote the absolute configuration of the molecule about its chiral center(s). The prefixes D and L, or (+) or (−), designate the sign of rotation of plane-polarized light by the compound, with L or (−) meaning that the compound is levorotatory. In contrast, a compound prefixed with D or (+) is dextrorotatory. There is no correlation between nomenclature for the absolute stereochemistry and for the rotation of an enantiomer. Thus, D-lactic acid is the same as (−)-lactic acid, and L-lactic acid is the same as (+)-lactic acid. For a given chemical structure, each of a pair of enantiomers are identical except that they are non-superimposable mirror images of one another. A specific stereoisomer may also be referred to as an enantiomer, and a mixture of such isomers is often called an enantiomeric, or racemic, mixture.
Stereochemical purity is important in the pharmaceutical field, where many of the most often prescribed drugs exhibit chirality. For example, the L-enantiomer of the beta-adrenergic blocking agent, propranolol, is known to be 100 times more potent than its D-enantiomer. Additionally, optical purity is important in the pharmaceutical drug field because certain isomers have been found to impart a deleterious effect, rather than an advantageous or inert effect. For example, it is believed that the D-enantiomer of thalidomide is a safe and effective sedative when prescribed for the control of morning sickness during pregnancy, whereas its corresponding L-enantiomer is believed to be a potent teratogen.
When two chiral centers exist in one molecule, there are four possible stereoisomers: (R,R), (S,S), (R,S), and (S,R). Of these, (R,R) and (S,S) are an example of a pair of enantiomers (mirror images of each other), which typically share chemical properties and melting points just like any other enantiomeric pair. The mirror images of (R,R) and (S,S) are not, however, superimposable on (R,S) and (S,R). This relationship is called diastereoisomeric, and the (S,S) molecule is a diastereoisomer of the (R,S) molecule, whereas the (R,R) molecule is a diastereoisomer of the (S,R) molecule.
An example of a compound with two chiral centers is the antimuscarinic solifenacin. Solifenacin is described in U.S. Pat. No. 6,174,896 and is represented by the following chemical formula:
Because solifenacin has two chiral centers, diastereomers as well as enantiomers exist for this molecule (see U.S. Pat. No. 6,174,896). Solifenacin succinate (development number YM-905) is a salt form of solifenacin that is co-promoted as Vesicare® by Yamanouchi Pharmaceutical Co., Ltd. (through Yamanouchi Pharma America) and GlaxoSmithKline as an investigational muscarinic antagonist. Solifenacin was discovered and developed by Yamanouchi, and a New Drug Application was submitted to the U.S. Food and Drug Administration by YPA in December 2002 for solifenacin succinate. A market authorization application for Vesicare® was submitted in Europe in January 2003, and Yamanouchi has initiated Phase III clinical trials for Vesicare® in Japan. Other salt forms of solifenacin have also been specifically described by Yamanouchi, including solifenacin monohydrochloride (development number YM-53705).
For use in the present invention, any diastereomer or enantiomer of an active agent as disclosed herein, can be administered to treat pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome.
Formulations
Formulations of the present invention may include, but are not limited to, continuous, as needed, short-term, rapid-offset, controlled release, sustained release, delayed release, and pulsatile release formulations.
Compositions of the invention comprise α2δ subunit calcium channel modulators in combination with one or more compounds with smooth muscle modulatory effects, including antimuscarinics (particularly those that do not have an amine embedded in an 8-azabicyclo[3.2.1]octan-3-ol skeleton), β3 adrenergic agonists, spasmolytics, neurokinin receptor antagonists, bradykinin receptor antagonists, and nitric oxide donors. The compositions are administered in therapeutically effective amounts to a patient in need thereof for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, as well as pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. It is recognized that the compositions may be administered by any means of administration as long as an effective amount for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, as well as pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome, is delivered.
Any of the active agents may be administered in the form of a salt, ester, amide, prodrug, active metabolite, derivative, or the like, provided that the salt, ester, amide, prodrug or derivative is suitable pharmacologically, i.e., effective in the present method. Salts, esters, amides, prodrugs and other derivatives of the active agents may be prepared using standard procedures known to those skilled in the art of synthetic organic chemistry and described, for example, by J. March, Advanced Organic Chemistry: Reactions, Mechanisms and Structure, 4th Ed. (New York: Wiley-Interscience, 1992). For example, acid addition salts are prepared from the free base using conventional methodology, and involves reaction with a suitable acid. Suitable acids for preparing acid addition salts include both organic acids, e.g., acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, malic acid, malonic acid, succinic acid, maleic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, and the like, as well as inorganic acids, e.g., hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like. An acid addition salt may be reconverted to the free base by treatment with a suitable base. Particularly preferred acid addition salts of the active agents herein are salts prepared with organic acids. Conversely, preparation of basic salts of acid moieties which may be present on an active agent are prepared in a similar manner using a pharmaceutically acceptable base such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, calcium hydroxide, trimethylamine, or the like.
Preparation of esters involves functionalization of hydroxyl and/or carboxyl groups that may be present within the molecular structure of the drug. The esters are typically acyl-substituted derivatives of free alcohol groups, i.e., moieties that are derived from carboxylic acids of the formula RCOOH where R is alkyl, and preferably is lower alkyl. Esters can be reconverted to the free acids, if desired, by using conventional hydrogenolysis or hydrolysis procedures. Amides and prodrugs may also be prepared using techniques known to those skilled in the art or described in the pertinent literature. For example, amides may be prepared from esters, using suitable amine reactants, or they may be prepared from an anhydride or an acid chloride by reaction with ammonia or a lower alkyl amine. Prodrugs are typically prepared by covalent attachment of a moiety, which results in a compound that is therapeutically inactive until modified by an individual's metabolic system.
One set of formulations for gabapentin are those marketed by Pfizer Inc. under the brand name Neurontin®. Neurontin® Capsules, Neurontin® Tablets, and Neurontin® Oral Solution are supplied either as imprinted hard shell capsules containing 100 mg, 300 mg, and 400 mg of gabapentin, elliptical film-coated tablets containing 600 mg and 800 mg of gabapentin or an oral solution containing 250 mg/5 mL of gabapentin. The inactive ingredients for the capsules are lactose, cornstarch, and talc. The 100 mg capsule shell contains gelatin and titanium dioxide. The 300 mg capsule shell contains gelatin, titanium dioxide, and yellow iron oxide. The 400 mg capsule shell contains gelatin, red iron oxide, titanium dioxide, and yellow iron oxide. The inactive ingredients for the tablets are poloxamer 407, copolyvidonum, cornstarch, magnesium stearate, hydroxypropyl cellulose, talc, candelilla wax and purified water. The inactive ingredients for the oral solution are glycerin, xylitol, purified water and artificial cool strawberry anise flavor. In addition to these formulations, gabapentin and formulations are generally described in the following patents: U.S. Pat. No. 6,683,112; U.S. Pat. No. 6,645,528; U.S. Pat. No. 6,627,211; U.S. Pat. No. 6,569,463; U.S. Pat. No. 6,544,998; U.S. Pat. Nos. 6,531,509; 6,495,669; U.S. Pat. No. 6,465,012; U.S. Pat. No. 6,346,270; U.S. Pat. No. 6,294,198; U.S. Pat. No. 6,294,192; U.S. Pat. No. 6,207,685; U.S. Pat. No. 6,127,418; U.S. Pat. No. 6,024,977; U.S. Pat. No. 6,020,370; U.S. Pat. No. 5,906,832; U.S. Pat. No. 5,876,750; and U.S. Pat. No. 4,960,931.
One set of formulations for oxybutynin are those marketed by Ortho-McNeil Pharmaceuticals, Inc. under the brand name Ditropan®. Ditropan® tablets are supplied containing 5 mg/tablets of the active ingredient, oxybutynin chloride, and the inactive ingredients anhydrous lactose, microcrystalline cellulose, calcium stearate, and FD&C blue #1 lake. Ditropan® syrup is supplied as 5 mg/5 mL of the active ingredient, oxybutynin chloride, and the inactive ingredients citric acid, FD&C green #3, flavor, glycerin, methylparaben, sodium citrate, sorbitol, sucrose, and water. Ditropan XL® is an extended release tablet form of Ditropan® supplied containing either 5 mg (pale yellow color) of oxybutynin chloride, 10 mg (pink color) of oxybutynin chloride, or 15 mg (gray color) of oxybutynin chloride. Inactive ingredients are cellulose acetate, hydroxypropyl methylcellulose, lactose, magnesium stearate, polyethylene glycol, polyethylene oxide, synthetic iron oxides, titanium dioxide, polysorbate 80, sodium chloride, and butylated hydroxytoluene.
Oxybutynin is also supplied by Watson Pharmaceuticals under the brand name Oxytrol® (oxybutynin transdermal system). Oxytrol® is a transdermal patch designed to deliver oxybutynin continuously and consistently over a 3 to 4 day interval. It is supplied as a 39 cm2 patch containing 36 mg of oxybutynin, which is designed to deliver 3.9 mg/day. The patch is worn continuously, and a new patch is applied every 3 to 4 days.
A formulation useful in the present invention comprises a combination of gabapentin and oxybutynin chloride. The combination can be supplied in various pharmaceutical composition and dosage forms as described herein. One formulation for supplying the combination is in a tablet formulation. Additional formulations for the combination of the present invention, such as capsules, syrups, etc. are also envisioned for delivery of the combination, and any description of tablet formulations is in no way meant to be limiting of possible delivery modes for the combination of the present invention.
Tablet formulations useful for supplying the gabapentin/oxybutynin combination useful in the present invention can comprise, in addition to the active ingredients in combination, functional excipients. Such excipients as are useful for preparing pharmaceutical compositions in a tablet formulation are known in the art and include compounds known to be useful as fillers, binders, lubricants, disintegrants, diluents, coatings, plastizers, glidants, compression aids, stabilizers, sweeteners, solubilizers, and other excipients that would be known to one of skill in the pharmaceutical arts.
The active ingredients of the combination useful in the present invention (gabapentin and oxybutynin) can be combined, particularly in tablet form, according to ratios provided herein. The relative ratio of the active ingredients of the combination for use in the present invention is about 1:1 to about 1:800, oxybutynin and gabapentin respectively, more preferably about 2.5:200 to 2.5:800, oxybutynin and gabapentin respectively. Generally, the ratio of oxybutynin to gabapentin in the combination is about 2.5:50, about 2.5:100, about 2.5:150, about 2.5:200, about 2.5:250, about 2.5:300, about 2.5:350, about 2.5:400, about 2.5:450, about 2.5:500, about 2.5:550, about 2.5:600, about 2.5:650, about 2.5:700, about 2.5:750, or about 2.5:800. Alternately, the ratio of oxybutynin to gabapentin in the combination is about about 1.25:50, about 1.25:100, about 1.25:150, about 1.25:200, about 1.25:250, about 1.25:300, about 1.25:350, about 1.25:400, about 1.25:450, about 1.25:500, about 1.25:550, about 1.25:600, about 1.25:650, about 1.25:700, about 1.25:750, or about 1.25:800. Alternately, the ratio of oxybutynin to gabapentin in the combination is about about 5:50, about 5:100, about 5:150, about 5:200, about 5:250, about 5:300, about 5:350, about 5:400, about 5:450, about 5:500, about 5:550, about 5:600, about 5:650, about 5:700, about 5:750, or about 5:800. Examples of formulations for preparing tablets comprising gabapentin and oxybutynin in combination suitable for use in the present invention are provided below in Tables 1 and 2.
Tablets according to the above formulations can be prepared according to a number of possible methods. One method used in preparing a tablet comprising a formulation as provided above includes the following steps:
Other derivatives and analogs of the active agents may be prepared using standard techniques known to those skilled in the art of synthetic organic chemistry, or may be deduced by reference to the pertinent literature. In addition, chiral active agents may be in isomerically pure form, or they may be administered as a racemic mixture of isomers.
Pharmaceutical Compositions and Dosage Forms
Suitable compositions and dosage forms include tablets, capsules, caplets, pills, gel caps, troches, dispersions, suspensions, solutions, syrups, transdermal patches, gels, powders, magmas, lozenges, creams, pastes, plasters, lotions, discs, suppositories, liquid sprays for nasal or oral administration, dry powder or aerosolized formulations for inhalation, compositions and formulations for intravesical administration and the like. Further, those of ordinary skill in the art can readily deduce that suitable formulations involving these compositions and dosage forms, including those formulations as described elsewhere herein.
Oral Dosage Forms
Oral dosage forms include tablets, capsules, caplets, solutions, suspensions and/or syrups, and may also comprise a plurality of granules, beads, powders or pellets that may or may not be encapsulated. Such dosage forms are prepared using conventional methods known to those in the field of pharmaceutical formulation and described in the pertinent texts, e.g., in Remington: The Science and Practice of Pharmacy, supra). Tablets and capsules represent the most convenient oral dosage forms, in which case solid pharmaceutical carriers are employed.
Tablets may be manufactured using standard tablet processing procedures and equipment. One method for forming tablets is by direct compression of a powdered, crystalline or granular composition containing the active agent(s), alone or in combination with one or more carriers, additives, or the like. As an alternative to direct compression, tablets can be prepared using wet-granulation or dry-granulation processes. Tablets may also be molded rather than compressed, starting with a moist or otherwise tractable material; however, compression and granulation techniques are preferred.
In addition to the active agent(s), then, tablets prepared for oral administration using the method of the invention will generally contain other materials such as binders, diluents, lubricants, disintegrants, fillers, stabilizers, surfactants, preservatives, coloring agents, flavoring agents and the like. Binders are used to impart cohesive qualities to a tablet, and thus ensure that the tablet remains intact after compression. Suitable binder materials include, but are not limited to, starch (including corn starch and pregelatinized starch), gelatin, sugars (including sucrose, glucose, dextrose and lactose), polyethylene glycol, propylene glycol, waxes, and natural and synthetic gums, e.g., acacia sodium alginate, polyvinylpyrrolidone, cellulosic polymers (including hydroxypropyl cellulose, hydroxypropyl methylcellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and the like), and Veegum. Diluents are typically necessary to increase bulk so that a practical size tablet is ultimately provided. Suitable diluents include dicalcium phosphate, calcium sulfate, lactose, cellulose, kaolin, mannitol, sodium chloride, dry starch and powdered sugar. Lubricants are used to facilitate tablet manufacture; examples of suitable lubricants include, for example, vegetable oils such as peanut oil, cottonseed oil, sesame oil, olive oil, corn oil, and oil of theobroma, glycerin, magnesium stearate, calcium stearate, and stearic acid. Stearates, if present, preferably represent at no more than approximately 2 wt. % of the drug-containing core. Disintegrants are used to facilitate disintegration of the tablet, and are generally starches, clays, celluloses, algins, gums or crosslinked polymers. Fillers include, for example, materials such as silicon dioxide, titanium dioxide, alumina, talc, kaolin, powdered cellulose and microcrystalline cellulose, as well as soluble materials such as mannitol, urea, sucrose, lactose, dextrose, sodium chloride and sorbitol. Stabilizers are used to inhibit or retard drug decomposition reactions that include, by way of example, oxidative reactions. Surfactants may be anionic, cationic, amphoteric or nonionic surface active agents.
The dosage form may also be a capsule, in which case the active agent-containing composition may be encapsulated in the form of a liquid or solid (including particulates such as granules, beads, powders or pellets). Suitable capsules may be either hard or soft, and are generally made of gelatin, starch, or a cellulosic material, with gelatin capsules preferred. Two-piece hard gelatin capsules are preferably sealed, such as with gelatin bands or the like. (See, for e.g., Remington: The Science and Practice of Pharmacy, supra), which describes materials and methods for preparing encapsulated pharmaceuticals. If the active agent-containing composition is present within the capsule in liquid form, a liquid carrier is necessary to dissolve the active agent(s). The carrier must be compatible with the capsule material and all components of the pharmaceutical composition, and must be suitable for ingestion.
Solid dosage forms, whether tablets, capsules, caplets, or particulates, may, if desired, be coated so as to provide for delayed release. Dosage forms with delayed release coatings may be manufactured using standard coating procedures and equipment. Such procedures are known to those skilled in the art and described in the pertinent texts (See, for e.g., Remington: The Science and Practice of Pharmacy, supra). Generally, after preparation of the solid dosage form, a delayed release coating composition is applied using a coating pan, an airless spray technique, fluidized bed coating equipment, or the like. Delayed release coating compositions comprise a polymeric material, e.g., cellulose butyrate phthalate, cellulose hydrogen phthalate, cellulose proprionate phthalate, polyvinyl acetate phthalate, cellulose acetate phthalate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, hydroxypropyl methylcellulose acetate, dioxypropyl methylcellulose succinate, carboxymethyl ethylcellulose, hydroxypropyl methylcellulose acetate succinate, polymers and copolymers formed from acrylic acid, methacrylic acid, and/or esters thereof.
Sustained release dosage forms provide for drug release over an extended time period, and may or may not be delayed release. Generally, as will be appreciated by those of ordinary skill in the art, sustained release dosage forms are formulated by dispersing a drug within a matrix of a gradually bioerodible (hydrolyzable) material such as an insoluble plastic, a hydrophilic polymer, or a fatty compound, or by coating a solid, drug-containing dosage form with such a material. Insoluble plastic matrices may be comprised of, for example, polyvinyl chloride or polyethylene. Hydrophilic polymers useful for providing a sustained release coating or matrix cellulosic polymers include, without limitation: cellulosic polymers such as hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, cellulose acetate, cellulose acetate phthalate, cellulose acetate trimellitate, hydroxypropylmethyl cellulose phthalate, hydroxypropylcellulose phthalate, cellulose hexahydrophthalate, cellulose acetate hexahydrophthalate, and carboxymethylcellulose sodium; acrylic acid polymers and copolymers, preferably formed from acrylic acid, methacrylic acid, acrylic acid alkyl esters, methacrylic acid alkyl esters, and the like, e.g. copolymers of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate and/or ethyl methacrylate, with a terpolymer of ethyl acrylate, methyl methacrylate and trimethylammonioethyl methacrylate chloride (sold under the tradename Eudragit RS) preferred; vinyl polymers and copolymers such as polyvinyl pyrrolidone, polyvinyl acetate, polyvinylacetate phthalate, vinylacetate crotonic acid copolymer, and ethylene-vinyl acetate copolymers; zein; and shellac, ammoniated shellac, shellac-acetyl alcohol, and shellac n-butyl stearate. Fatty compounds for use as a sustained release matrix material include, but are not limited to, waxes generally (e.g., carnauba wax) and glyceryl tristearate.
Transmucosal Compositions and Dosage Forms
Although the present compositions may be administered orally, other modes of administration are suitable as well. For example, transmucosal administration may be advantageously employed. Transmucosal administration is carried out using any type of formulation or dosage unit suitable for application to mucosal tissue. For example, the selected active agent may be administered to the buccal mucosa in an adhesive tablet or patch, sublingually administered by placing a solid dosage form under the tongue, lingually administered by placing a solid dosage form on the tongue, administered nasally as droplets or a nasal spray, administered by inhalation of an aerosol formulation, a non-aerosol liquid formulation, or a dry powder, placed within or near the rectum (“transrectal” formulations), or administered to the urethra as a suppository, ointment, or the like.
Preferred buccal dosage forms will typically comprise a therapeutically effective amount of an active agent and a bioerodible (hydrolyzable) polymeric carrier that may also serve to adhere the dosage form to the buccal mucosa. The buccal dosage unit is fabricated so as to erode over a predetermined time period, wherein drug delivery is provided essentially throughout. The time period is typically in the range of from about 1 hour to about 72 hours. Preferred buccal delivery preferably occurs over a time period of from about 2 hours to about 24 hours. Buccal drug delivery for short term use should preferably occur over a time period of from about 2 hours to about 8 hours, more preferably over a time period of from about 3 hours to about 4 hours. As needed buccal drug delivery preferably will occur over a time period of from about 1 hour to about 12 hours, more preferably from about 2 hours to about 8 hours, most preferably from about 3 hours to about 6 hours. Sustained buccal drug delivery will preferably occur over a time period of from about 6 hours to about 72 hours, more preferably from about 12 hours to about 48 hours, most preferably from about 24 hours to about 48 hours. Buccal drug delivery, as will be appreciated by those skilled in the art, avoids the disadvantages encountered with oral drug administration, e.g., slow absorption, degradation of the active agent by fluids present in the gastrointestinal tract and/or first-pass inactivation in the liver.
The “therapeutically effective amount” of the active agent in the buccal dosage unit will of course depend on the potency of the agent and the intended dosage, which, in turn, is dependent on the particular individual undergoing treatment, the specific indication, and the like. The buccal dosage unit will generally contain from about 1.0 wt. % to about 60 wt. % active agent, preferably on the order of from about 1 wt. % to about 30, wt. % active agent. With regard to the bioerodible (hydrolyzable) polymeric carrier, it will be appreciated that virtually any such carrier can be used, so long as the desired drug release profile is not compromised, and the carrier is compatible with the active agents to be administered and any other components of the buccal dosage unit. Generally, the polymeric carrier comprises a hydrophilic (water-soluble and water-swellable) polymer that adheres to the wet surface of the buccal mucosa. Examples of polymeric carriers useful herein include acrylic acid polymers and co, e.g., those known as “carbomers” (Carbopol®, which may be obtained from B.F. Goodrich, is one such polymer). Other suitable polymers include, but are not limited to: hydrolyzed polyvinylalcohol; polyethylene oxides (e.g., Sentry Polyox® water soluble resins, available from Union Carbide); polyacrylates (e.g., Gantrez®, which may be obtained from GAF); vinyl polymers and copolymers; polyvinylpyrrolidone; dextran; guar gum; pectins; starches; and cellulosic polymers such as hydroxypropyl methylcellulose, (e.g., Methocel®, which may be obtained from the Dow Chemical Company), hydroxypropyl cellulose (e.g., Klucel®, which may also be obtained from Dow), hydroxypropyl cellulose ethers (see, e.g., U.S. Pat. No. 4,704,285 to Alderman), hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, methyl cellulose, ethyl cellulose, cellulose acetate phthalate, cellulose acetate butyrate, and the like.
Other components may also be incorporated into the buccal dosage forms described herein. The additional components include, but are not limited to, disintegrants, diluents, binders, lubricants, flavoring, colorants, preservatives, and the like. Examples of disintegrants that may be used include, but are not limited to, cross-linked polyvinylpyrrolidones, such as crospovidone (e.g., Polyplasdone® XL, which may be obtained from GAF), cross-linked carboxylic methylcelluloses, such as croscarmelose (e.g., Ac-di-sol®, which may be obtained from FMC), alginic acid, and sodium carboxymethyl starches (e.g., Explotab®, which may be obtained from Edward Medell Co., Inc.), methylcellulose, agar bentonite and alginic acid. Suitable diluents are those which are generally useful in pharmaceutical formulations prepared using compression techniques, e.g., dicalcium phosphate dihydrate (e.g., Di-Tab®, which may be obtained from Stauffer), sugars that have been processed by cocrystallization with dextrin (e.g., co-crystallized sucrose and dextrin such as Di-Pak®, which may be obtained from Amstar), calcium phosphate, cellulose, kaolin, mannitol, sodium chloride, dry starch, powdered sugar and the like. Binders, if used, are those that enhance adhesion. Examples of such binders include, but are not limited to, starch, gelatin and sugars such as sucrose, dextrose, molasses, and lactose. Particularly preferred lubricants are stearates and stearic acid, and an optimal lubricant is magnesium stearate.
Sublingual and lingual dosage forms include tablets, creams, ointments, lozenges, pastes, and any other solid dosage form where the active ingredient is admixed into a disintegrable matrix. The tablet, cream, ointment or paste for sublingual or lingual delivery comprises a therapeutically effective amount of the selected active agent and one or more conventional nontoxic carriers suitable for sublingual or lingual drug administration. The sublingual and lingual dosage forms of the present invention can be manufactured using conventional processes. The sublingual and lingual dosage units are fabricated to disintegrate rapidly. The time period for complete disintegration of the dosage unit is typically in the range of from about 10 seconds to about 30 minutes, and optimally is less than 5 minutes.
Other components may also be incorporated into the sublingual and lingual dosage forms described herein. The additional components include, but are not limited to binders, disintegrants, wetting agents, lubricants, and the like. Examples of binders that may be used include water, ethanol, polyvinylpyrrolidone; starch solution gelatin solution, and the like. Suitable disintegrants include dry starch, calcium carbonate, polyoxyethylene sorbitan fatty acid esters, sodium lauryl sulfate, stearic monoglyceride, lactose, and the like. Wetting agents, if used, include glycerin, starches, and the like. Particularly preferred lubricants are stearates and polyethylene glycol. Additional components that may be incorporated into sublingual and lingual dosage forms are known, or will be apparent, to those skilled in this art (See, e.g., Remington: The Science and Practice of Pharmacy, supra).
For transurethral administration, the formulation comprises a urethral dosage form containing the active agent and one or more selected carriers or excipients, such as water, silicone, waxes, petroleum jelly, polyethylene glycol (“PEG”), propylene glycol (“PG”), liposomes, sugars such as mannitol and lactose, and/or a variety of other materials, with polyethylene glycol and derivatives thereof particularly preferred.
Depending on the particular active agent administered, it may be desirable to incorporate a transurethral permeation enhancer in the urethral dosage form. Examples of suitable transurethral permeation enhancers include dimethylsulfoxide (“DMSO”), dimethyl formamide (“DMF”), N,N-dimethylacetamide (“DMA”), decylmethylsulfoxide (“C10 MSO”), polyethylene glycol monolaurate (“PEGML”), glycerol monolaurate, lecithin, the 1-substituted azacycloheptan-2-ones, particularly 1-n-dodecylcyclazacycloheptan-2-one (available under the trademark Azone® from Nelson Research & Development Co., Irvine, Calif.), SEPA® (available from Macrochem Co., Lexington, Mass.), surfactants as discussed above, including, for example, Tergitol®, Nonoxynol-9® and TWEEN-80®, and lower alkanols such as ethanol.
Transurethral drug administration, as explained in U.S. Pat. Nos. 5,242,391, 5,474,535, 5,686,093 and 5,773,020, can be carried out in a number of different ways using a variety of urethral dosage forms. For example, the drug can be introduced into the urethra from a flexible tube, squeeze bottle, pump or aerosol spray. The drug may also be contained in coatings, pellets or suppositories that are absorbed, melted or bioeroded in the urethra. In certain embodiments, the drug is included in a coating on the exterior surface of a penile insert. It is preferred, although not essential, that the drug be delivered from at least about 3 cm into the urethra, and preferably from at least about 7 cm into the urethra. Generally, delivery from at least about 3 cm to about 8 cm into the urethra will provide effective results in conjunction with the present method.
Urethral suppository formulations containing PEG or a PEG derivative may be conveniently formulated using conventional techniques, e.g., compression molding, heat molding or the like, as will be appreciated by those skilled in the art and as described in the pertinent literature and pharmaceutical texts. (See, e.g., Remington: The Science and Practice of Pharmacy, supra), which discloses typical methods of preparing pharmaceutical compositions in the form of urethral suppositories. The PEG or PEG derivative preferably has a molecular weight in the range of from about 200 to about 2,500 g/mol, more preferably in the range of from about 1,000 to about 2,000 g/mol, Suitable polyethylene glycol derivatives include polyethylene glycol fatty acid esters, for example, polyethylene glycol monostearate, polyethylene glycol sorbitan esters, e.g., polysorbates, and the like. Depending on the particular active agent, it may also be preferred that urethral suppositories contain one or more solubilizing agents effective to increase the solubility of the active agent in the PEG or other transurethral vehicle.
It may be desirable to deliver the active agent in a urethral dosage form that provides for controlled or sustained release of the agent. In such a case, the dosage form comprises a biocompatible, biodegradable material, typically a biodegradable polymer. Examples of such polymers include polyesters, polyalkylcyanoacrylates, polyorthoesters, polyanhydrides, albumin, gelatin and starch. As explained, for example, in PCT Publication No. WO 96/40054, these and other polymers can be used to provide biodegradable microparticles that enable controlled and sustained drug release, in turn minimizing the required dosing frequency.
The urethral dosage form will preferably comprise a suppository that is on the order of from about 2 to about 20 mm in length, preferably from about 5 to about 10 mm in length, and less than about 5 mm in width, preferably less than about 2 mm in width. The weight of the suppository will typically be in the range of from about 1 mg to about 100 mg, preferably in the range of from about 1 mg to about 50 mg. However, it will be appreciated by those skilled in the art that the size of the suppository can and will vary, depending on the potency of the drug, the nature of the formulation, and other factors.
Transurethral drug delivery may involve an “active” delivery mechanism such as iontophoresis, electroporation or phonophoresis. Devices and methods for delivering drugs in this way are well known in the art. Iontophoretically assisted drug delivery is, for example, described in PCT Publication No. WO 96/40054, cited above. Briefly, the active agent is driven through the urethral wall by means of an electric current passed from an external electrode to a second electrode contained within or affixed to a urethral probe.
Preferred transrectal dosage forms include rectal suppositories, creams, ointments, and liquid formulations (enemas). The suppository, cream, ointment or liquid formulation for transrectal delivery comprises a therapeutically effective amount of the selected phosphodiesterase inhibitor and one or more conventional nontoxic carriers suitable for transrectal drug administration. The transrectal dosage forms of the present invention can be manufactured using conventional processes. The transrectal dosage unit can be fabricated to disintegrate rapidly or over a period of several hours. The time period for complete disintegration is preferably in the range of from about 10 minutes to about 6 hours, and optimally is less than about 3 hours.
Other components may also be incorporated into the transrectal dosage forms described herein. The additional components include, but are not limited to, stiffening agents, antioxidants, preservatives, and the like. Examples of stiffening agents that may be used include, for example, paraffin, white wax and yellow wax. Preferred antioxidants, if used, include sodium bisulfite and sodium metabisulfite.
Preferred vaginal or perivaginal dosage forms include vaginal suppositories, creams, ointments, liquid formulations, pessaries, tampons, gels, pastes, foams or sprays. The suppository, cream, ointment, liquid formulation, pessary, tampon, gel, paste, foam or spray for vaginal or perivaginal delivery comprises a therapeutically effective amount of the selected active agent and one or more conventional nontoxic carriers suitable for vaginal or perivaginal drug administration. The vaginal or perivaginal forms of the present invention can be manufactured using conventional processes as disclosed in Remington: The Science and Practice of Pharmacy, supra (see also drug formulations as adapted in U.S. Pat. Nos. 6,515,198; 6,500,822; 6,417,186; 6,416,779; 6,376,500; 6,355,641; 6,258,819; 6,172,062; and 6,086,909). The vaginal or perivaginal dosage unit can be fabricated to disintegrate rapidly or over a period of several hours. The time period for complete disintegration is preferably in the range of from about 10 minutes to about 6 hours, and optimally is less than about 3 hours.
Other components may also be incorporated into the vaginal or perivaginal dosage forms described herein. The additional components include, but are not limited to, stiffening agents, antioxidants, preservatives, and the like. Examples of stiffening agents that may be used include, for example, paraffin, white wax and yellow wax. Preferred antioxidants, if used, include sodium bisulfite and sodium metabisulfite.
The active agents may also be administered intranasally or by inhalation. Compositions for intranasal administration are generally liquid formulations for administration as a spray or in the form of drops, although powder formulations for intranasal administration, e.g., insufflations, are also known, as are nasal gels, creams, pastes or ointments. For liquid formulations, the active agent can be formulated into a solution, e.g., water or isotonic saline, buffered or unbuffered, or as a suspension. Preferably, such solutions or suspensions are isotonic relative to nasal secretions and of about the same pH, ranging e.g., from about pH 4.0 to about pH 7.4 or, from about pH 6.0 to about pH 7.0. Buffers should be physiologically compatible and include, simply by way of example, phosphate buffers. Furthermore, various devices are available in the art for the generation of drops, droplets and sprays, including droppers, squeeze bottles, and manually and electrically powered intranasal pump dispensers. Active agent containing intranasal carriers may also include nasal gels, creams, pastes or ointments with a viscosity of, e.g., from about 10 to about 6500 cps, or greater, depending on the desired sustained contact with the nasal mucosal surfaces. Such carrier viscous formulations may be based upon, simply by way of example, alkylcelluloses and/or other biocompatible carriers of high viscosity well known to the art (see e.g., Remington: The Science and Practice of Pharmacy, supra). Other ingredients, such as art known preservatives, colorants, lubricating or viscous mineral or vegetable oils, perfumes, natural or synthetic plant extracts such as aromatic oils, and humectants and viscosity enhancers such as, e.g., glycerol, can also be included to provide additional viscosity, moisture retention and a pleasant texture and odor for the formulation. Formulations for inhalation may be prepared as an aerosol, either a solution aerosol in which the active agent is solubilized in a carrier (e.g., propellant) or a dispersion aerosol in which the active agent is suspended or dispersed throughout a carrier and an optional solvent. Non-aerosol formulations for inhalation may take the form of a liquid, typically an aqueous suspension, although aqueous solutions may be used as well. In such a case, the carrier is typically a sodium chloride solution having a concentration such that the formulation is isotonic relative to normal body fluid. In addition to the carrier, the liquid formulations may contain water and/or excipients including an antimicrobial preservative (e.g., benzalkonium chloride, benzethonium chloride, chlorobutanol, phenylethyl alcohol, thimerosal and combinations thereof), a buffering agent (e.g., citric acid, potassium metaphosphate, potassium phosphate, sodium acetate, sodium citrate, and combinations thereof), a surfactant (e.g., polysorbate 80, sodium lauryl sulfate, sorbitan monopalmitate and combinations thereof), and/or a suspending agent (e.g., agar, bentonite, microcrystalline cellulose, sodium carboxymethylcellulose, hydroxypropyl methylcellulose, tragacanth, veegum and combinations thereof). Non-aerosol formulations for inhalation may also comprise dry powder formulations, particularly insufflations in which the powder has an average particle size of from about 0.1 μm to about 50 μm, preferably from about 1 μm to about 25 μm.
Topical Formulations
Topical formulations may be in any form suitable for application to the body surface, and may comprise, for example, an ointment, cream, gel, lotion, solution, paste or the like, and/or may be prepared so as to contain liposomes, micelles, and/or microspheres. Preferred topical formulations herein are ointments, creams and gels.
Ointments, as is well known in the art of pharmaceutical formulation, are semisolid preparations that are typically based on petrolatum or other petroleum derivatives. The specific ointment base to be used, as will be appreciated by those skilled in the art, is one that will provide for optimum drug delivery, and, preferably, will provide for other desired characteristics as well, e.g., emolliency or the like. As with other carriers or vehicles, an ointment base should be inert, stable, nonirritating and nonsensitizing. As explained in Remington: The Science and Practice of Pharmacy, supra, ointment bases may be grouped in four classes: oleaginous bases; emulsifiable bases; emulsion bases; and water-soluble bases. Oleaginous ointment bases include, for example, vegetable oils, fats obtained from animals, and semisolid hydrocarbons obtained from petroleum. Emulsifiable ointment bases, also known as absorbent ointment bases, contain little or no water and include, for example, hydroxystearin sulfate, anhydrous lanolin and hydrophilic petrolatum. Emulsion ointment bases are either water-in-oil (W/O) emulsions or oil-in-water (O/W) emulsions, and include, for example, cetyl alcohol, glyceryl monostearate, lanolin and stearic acid. Preferred water-soluble ointment bases are prepared from polyethylene glycols of varying molecular weight (See, e.g., Remington: The Science and Practice of Pharmacy, supra).
Creams, as also well known in the art, are viscous liquids or semisolid emulsions, either oil-in-water or water-in-oil. Cream bases are water-washable, and contain an oil phase, an emulsifier and an aqueous phase. The oil phase, also called the “internal” phase, is generally comprised of petrolatum and a fatty alcohol such as cetyl or stearyl alcohol. The aqueous phase usually, although not necessarily, exceeds the oil phase in volume, and generally contains a humectant. The emulsifier in a cream formulation is generally a nonionic, anionic, cationic or amphoteric surfactant.
As will be appreciated by those working in the field of pharmaceutical formulation, gels-are semisolid, suspension-type systems. Single-phase gels contain organic macromolecules distributed substantially uniformly throughout the carrier liquid, which is typically aqueous, but also, preferably, contain an alcohol and, optionally, an oil. Preferred “organic macromolecules,” i.e., gelling agents, are crosslinked acrylic acid polymers such as the “carbomer” family of polymers, e.g., carboxypolyalkylenes that may be obtained commercially under the Carbopol® trademark. Also preferred are hydrophilic polymers such as polyethylene oxides, polyoxyethylene-polyoxypropylene copolymers and polyvinylalcohol; cellulosic polymers such as hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose, hydroxypropyl methylcellulose phthalate, and methylcellulose; gums such as tragacanth and xanthan gum; sodium alginate; and gelatin. In order to prepare a uniform gel, dispersing agents such as alcohol or glycerin can be added, or the gelling agent can be dispersed by trituration, mechanical mixing, and/or stirring.
Various additives, known to those skilled in the art, may be included in the topical formulations. For example, solubilizers may be used to solubilize certain active agents. For those drugs having an unusually low rate of permeation through the skin or mucosal tissue, it may be desirable to include a permeation enhancer in the formulation; suitable enhancers are as described elsewhere herein.
Transdermal Administration
The compounds of the invention may also be administered through the skin or mucosal tissue using conventional transdermal drug delivery systems, wherein the agent is contained within a laminated structure (typically referred to as a transdermal “patch”) that serves as a drug delivery device to be affixed to the skin. Transdermal drug delivery may involve passive diffusion or it may be facilitated using electrotransport, e.g., iontophoresis. In a typical transdermal “patch,” the drug composition is contained in a layer, or “reservoir,” underlying an upper backing layer. The laminated structure may contain a single reservoir, or it may contain multiple reservoirs. In one type of patch, referred to as a “monolithic” system, the reservoir is comprised of a polymeric matrix of a pharmaceutically acceptable contact adhesive material that serves to affix the system to the skin during drug delivery. Examples of suitable skin contact adhesive materials include, but are not limited to, polyethylenes, polysiloxanes, polyisobutylenes, polyacrylates, polyurethanes, and the like. Alternatively, the drug-containing reservoir and skin contact adhesive are separate and distinct layers, with the adhesive underlying the reservoir which, in this case, may be either a polymeric matrix as described above, or it may be a liquid or hydrogel reservoir, or may take some other form.
The backing layer in these laminates, which serves as the upper surface of the device, functions as the primary structural element of the laminated structure and provides the device with much of its flexibility. The material selected for the backing material should be selected so that it is substantially impermeable to the active agent and any other materials that are present, the backing is preferably made of a sheet or film of a flexible elastomeric material. Examples of polymers that are suitable for the backing layer include polyethylene, polypropylene, polyesters, and the like.
During storage and prior to use, the laminated structure includes a release liner. Immediately prior to use, this layer is removed from the device to expose the basal surface thereof, either the drug reservoir or a separate contact adhesive layer, so that the system may be affixed to the skin. The release liner should be made from a drug/vehicle impermeable material.
Transdermal drug delivery systems may in addition contain a skin permeation enhancer. That is, because the inherent permeability of the skin to some drugs may be too low to allow therapeutic levels of the drug to pass through a reasonably sized area of unbroken skin, it is necessary to coadminister a skin permeation enhancer with such drugs. Suitable enhancers are well known in the art and include, for example, hose enhancers listed above in transmucosal compositions.
Parenteral Administration
Parenteral administration, if used, is generally characterized by injection, including intramuscular, intraperitoneal, intravenous (IV) and subcutaneous injection. Injectable formulations can be prepared in conventional forms, either as liquid solutions or suspensions; solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions. Preferably, sterile injectable suspensions are formulated according to techniques known in the art using suitable dispersing or wetting agents and suspending agents. The sterile injectable formulation may also be a sterile injectable solution or a suspension in a nontoxic parenterally acceptable diluent or solvent. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. A more recently revised approach for parenteral administration involves use of a slow release or sustained release system (See, e.g., U.S. Pat. No. 3,710,795).
Intravesical Administration
Intravesical administration, if used, is generally characterized by administration directly into the bladder and may include methods as described elsewhere herein. Other methods of intravesical administration may include those described in U.S. Pat. Nos. 6,207,180 and 6,039,967, as well as other methods that are known to one of skill in the art.
Intrathecal Administration
Intrathecal administration, if used, is generally characterized by administration directly into the intrathecal space (where fluid flows around the spinal cord).
One common system utilized for intrathecal administration is the APT Intrathecal treatment system available from Medtronic, Inc. APT Intrathecal uses a small pump that is surgically placed under the skin of the abdomen to deliver medication directly into the intrathecal space. The medication is delivered through a small tube called a catheter that is also surgically placed. The medication can then be administered directly to cells in the spinal cord involved in conveying sensory and motor signals.
Another system available from Medtronic that is commonly utilized for intrathecal administration is the is the fully implantable, programmable SynchroMed® Infusion System. The SynchroMed® Infusion System has two parts that are both placed in the body during a surgical procedure: the catheter and the pump. The catheter is a small, soft tube. One end is connected to the catheter port of the pump, and the other end is placed in the intrathecal space. The pump is a round metal device about one inch (2.5 cm) thick, three inches (8.5 cm) in diameter, and weighs about six ounces (205 g) that stores and releases prescribed amounts of medication directly into the intrathecal space. It is made of titanium, a lightweight, medical-grade metal. The reservoir is the space inside the pump that holds the medication. The fill port is a raised center portion of the pump through which the pump is refilled. The doctor or a nurse inserts a needle through the patient's skin and through the fill port to fill the pump. Some pumps have a side catheter access port that allows the doctor to inject other medications or sterile solutions directly into the catheter, bypassing the pump.
The SynchroMed® pump automatically delivers a controlled amount of medication through the catheter to the intrathecal space around the spinal cord, where it is most effective. The exact dosage, rate and timing prescribed by the doctor are entered in the pump using a programmer, an external computer-like device that controls the pump's memory. Information about the patient's prescription is stored in the pump's memory. The doctor can easily review this information by using the programmer. The programmer communicates with the pump by radio signals that allow the doctor to tell how the pump is operating at any given time. The doctor also can use the programmer to change your medication dosage.
Methods of intrathecal administration may include those described above available from Medtronic, as well as other methods that are known to one of skill in the art.
Additional Dosage Formulations and Drug Delivery Systems
As compared with traditional drug delivery approaches, some controlled release technologies rely upon the modification of both macromolecules and synthetic small molecules to allow them to be actively instead of passively absorbed into the body. For example, XenoPort Inc. utilizes technology that takes existing molecules and re-engineers them to create new chemical entities (unique molecules) that have improved pharmacologic properties to either: 1) lengthen the short half-life of a drug; 2) overcome poor absorption; and/or 3) deal with poor drug distribution to target tissues. Techniques to lengthen the short half-life of a drug include the use of prodrugs with slow cleavage rates to release drugs over time or that engage transporters in small and large intestines to allow the use of oral sustained delivery systems, as well as drugs that engage active transport systems. Examples of such controlled release formulations, tablets, dosage forms, and drug delivery systems, and that are suitable for use with the present invention, are described in the following published US and PCT patent applications assigned to Xenoport Inc.: US20030158254; US20030158089; US20030017964; US2003130246; WO02100172; WO02100392; WO02100347; WO02100344; WO0242414; WO0228881; WO0228882; WO0244324; WO0232376; WO0228883; and WO0228411. In particular, Xenoport's XP13512 is a transported Prodrug of gabapentin that has been engineered to utilize high capacity transport mechanisms located in both the small and large intestine and to rapidly convert to gabapentin once in the body. In contrast to gabapentin itself, XP13512 was shown in preclinical and clinical studies to produce dose proportional blood levels of gabapentin across a broad range of oral doses, and to be absorbed efficiently from the large intestine.
Some other controlled release technologies rely upon methods that promote or enhance gastric retention, such as those developed by Depomed Inc. Because many drugs are best absorbed in the stomach and upper portions of the small intestine, Depomed has developed tablets that swell in the stomach during the postprandial or fed mode so that they are treated like undigested food. These tablets therefore sit safely and neutrally in the stomach for 6, 8, or more hours and deliver drug at a desired rate and time to upper gastrointestinal sites. Specific technologies in this area include: 1) tablets that slowly erode in gastric fluids to deliver drugs at almost a constant rate (particularly useful for highly insoluble drugs); 2) bi-layer tablets that combine drugs with different characteristics into a single table (such as a highly insoluble drug in an erosion layer and a soluble drug in a diffusion layer for sustained release of both); and 3) combination tablets that can either deliver drugs simultaneously or in sequence over a desired period of time (including an initial burst of a fast acting drug followed by slow and sustained delivery of another drug). Examples of such controlled release formulations that are suitable for use with the present invention and that rely upon gastric retention during the postprandial or fed mode, include tablets, dosage forms, and drug delivery systems in the following US patents assigned to Depomed Inc.: U.S. Pat. No. 6,488,962; U.S. Pat. No. 6,451,808; U.S. Pat. No. 6,340,475; U.S. Pat. No. 5,972,389; U.S. Pat. No. 5,582,837; and U.S. Pat. No. 5,007,790. Examples of such controlled release formulations that are suitable for use with the present invention and that rely upon gastric retention during the postprandial or fed mode, include tablets, dosage forms, and drug delivery systems in the following published US and PCT patent applications assigned to Depomed Inc.: US20030147952; US20030104062; US20030104053; US20030104052; US20030091630; US20030044466; US20030039688; US20020051820; WO0335040; WO0335039; WO0156544; WO6132217; WO9855107; WO9747285; and WO9318755.
Other controlled release systems include those developed by ALZA Corporation based upon: 1) osmotic technology for oral delivery; 2) transdermal delivery via patches; 3) liposomal delivery via intravenous injection; 4) osmotic technology for long-term delivery via implants; and 5) depot technology designed to deliver agents for periods of days to a month. ALZA oral delivery systems include those that employ osmosis to provide precise, controlled drug delivery for up to 24 hours for both poorly soluble and highly soluble drugs, as well as those that deliver high drug doses meeting high drug loading requirements. ALZA controlled transdermal delivery systems provide drug delivery through intact skin for as long as one week with a single application to improve drug absorption and deliver constant amounts of drug into the bloodstream over time. ALZA liposomal delivery systems involve lipid nanoparticles that evade recognition by the immune system because of their unique polyethylene glycol (PEG) coating, allowing the precise delivery of drugs to disease-specific areas of the body. ALZA also has developed osmotically driven systems to enable the continuous delivery of small drugs, peptides, proteins, DNA and other bioactive macromolecules for up to one year for systemic or tissue-specific therapy. Finally, ALZA depot injection therapy is designed to deliver biopharmaceutical agents and small molecules for periods of days to a month using a nonaqueous polymer solution for the stabilization of macromolecules and a unique delivery profile.
Examples of controlled release formulations, tablets, dosage forms, and drug delivery systems that are suitable for use with the present invention are described in the following US patents assigned to ALZA Corporation: U.S. Pat. No. 4,367,741; U.S. Pat. No. 4,402,695; U.S. Pat. No. 4,418,038; U.S. Pat. No. 4,434,153; U.S. Pat. No. 4,439,199; U.S. Pat. No. 4,450,198; U.S. Pat. No. 4,455,142; U.S. Pat. No. 4,455,144; U.S. Pat. No. 4,484,923; U.S. Pat. No. 4,486,193; U.S. Pat. No. 4,489,197; U.S. Pat. No. 4,511,353; U.S. Pat. No. 4,519,801; U.S. Pat. No. 4,526,578; U.S. Pat. No. 4,526,933; U.S. Pat. No. 4,534,757; U.S. Pat. No. 4,553,973; U.S. Pat. No. 4,559,222; U.S. Pat. No. 4,564,364; U.S. Pat. No. 4,578,075; U.S. Pat. No. 4,588,580; U.S. Pat. No. 4,610,686; U.S. Pat. No. 4,612,008; U.S. Pat. No. 4,618,487; U.S. Pat. No. 4,627,851; U.S. Pat. No. 4,629,449; U.S. Pat. No. 4,642,233; U.S. Pat. No. 4,649,043; U.S. Pat. No. 4,650,484; U.S. Pat. No. 4,659,558; U.S. Pat. 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No. 6,572,879; and U.S. Pat. No. 6,596,314.
Other examples of controlled release formulations, tablets, dosage forms, and drug delivery systems that are suitable for use with the present invention are described in the following published US patent application and PCT applications assigned to ALZA Corporation: US20010051183; WO0004886; WO0013663; WO0013674; WO0025753; WO0025790; WO0035419; WO0038650; WO0040218; WO0045790; WO0066126; WO0074650; WO0119337; WO0119352; WO0121211; WO0137815; WO0141742; WO0143721; WO0156543; WO3041684; WO03041685; WO03041757; WO03045352; WO03051341; WO03053400; WO03053401; WO9000416; WO9004965; WO9113613; WO9116884; WO9204011; WO9211843; WO9212692; WO9213521; WO9217239; WO9218102; WO9300071; WO9305843; WO9306819; WO9314813; WO9319739; WO9320127; WO9320134; WO9407562; WO9408572; WO9416699; WO9421262; WO9427587; WO9427589; WO9503823; WO9519174; WO9529665; WO9600065; WO9613248; WO9625922; WO9637202; WO9640049; WO9640050; WO9640139; WO9640364; WO9640365; WO9703634; WO9800158; WO9802169; WO9814168; WO9816250; WO9817315; WO9827962; WO9827963; WO9843611; WO9907342; WO9912526; WO9912527; WO9918159; WO9929297; WO9929348; WO9932096; WO9932153; WO9948494; WO9956730; WO9958115; and WO9962496.
Another drug delivery technology suitable for use in the present invention is that disclosed by DepoMed, Inc. in U.S. Pat. No. 6,682,759, which discloses a method for manufacturing a pharmaceutical tablet for oral administration combining both immediate-release and prolonged-release modes of drug delivery. The tablet according to the method comprises a prolonged-release drug core and an immediate-release drug coating or layer, which can be insoluble or sparingly soluble in water. The method limits the drug particle diameter in the immediate-release coating or layer to 10 microns or less. The coating or layer is either the particles themselves, applied as an aqueous suspension, or a solid composition that contains the drug particles incorporated in a solid material that disintegrates rapidly in gastric fluid.
Andrx Corporation has also developed drug delivery technology suitable for use in the present invention that includes: 1) a pelletized pulsatile delivery system (“PPDS”); 2) a single composition osmotic tablet system (“SCOT”); 3) a solubility modulating hydrogel system (“SMHS”); 4) a delayed pulsatile hydrogel system (“DPHS”); 5) a stabilized pellet delivery system (“SPDS”); 6) a granulated modulating hydrogel system (“GMHS”); 7) a pelletized tablet system (“PELTAB”); 8) a porous tablet system (“PORTAB”); and 9) a stabilized tablet delivery system (“STDS”). PPDS uses pellets that are coated with specific polymers and agents to control the release rate of the microencapsulated drug and is designed for use with drugs that require a pulsed release. SCOT utilizes various osmotic modulating agents as well as polymer coatings to provide a zero-order drug release. SMHS utilizes a hydrogel-based dosage system that avoids the “initial burst effect” commonly observed with other sustained-release hydrogel formulations and that provides for sustained release without the need to use special coatings or structures that add to the cost of manufacturing. DPHS is designed for use with hydrogel matrix products characterized by an initial zero-order drug release followed by a rapid release that is achieved by the blending of selected hydrogel polymers to achieve a delayed pulse. SPDS incorporates a pellet core of drug and protective polymer outer layer, and is designed specifically for unstable drugs, while GMHS incorporates hydrogel and binding polymers with the drug and forms granules that are pressed into tablet form. PELTAB provides controlled release by using a water insoluble polymer to coat discrete drug crystals or pellets to enable them to resist the action of fluids in the gastrointestinal tract, and these coated pellets are then compressed into tablets. PORTAB provides controlled release by incorporating an osmotic core with a continuous polymer coating and a water soluble component that expands the core and creates microporous channels through which drug is released. Finally, STDS includes a dual layer coating technique that avoids the need to use a coating layer to separate the enteric coating layer from the omeprazole core.
Examples of controlled release formulations, tablets, dosage forms, and drug delivery systems that are suitable for use with the present invention are described in the following US patents assigned to Andrx Corporation: U.S. Pat. No. 5,397,574; U.S. Pat. No. 5,419,917; U.S. Pat. No. 5,458,887; U.S. Pat. No. 5,458,888; U.S. Pat. No. 5,472,708; U.S. Pat. No. 5,508,040; U.S. Pat. No. 5,558,879; U.S. Pat. No. 5,567,441; U.S. Pat. No. 5,654,005; U.S. Pat. No. 5,728,402; U.S. Pat. No. 5,736,159; U.S. Pat. No. 5,830,503; U.S. Pat. No. 5,834,023; U.S. Pat. No. 5,837,379; U.S. Pat. No. 5,916,595; U.S. Pat. No. 5,922,352; U.S. Pat. No. 6,099,859; U.S. Pat. No. 6,099,862; U.S. Pat. No. 6,103,263; U.S. Pat. No. 6,106,862; U.S. Pat. No. 6,156,342; U.S. Pat. No. 6,177,102; U.S. Pat. No. 6,197,347; U.S. Pat. No. 6,210,716; U.S. Pat. No. 6,238,703; U.S. Pat. No. 6,270,805; U.S. Pat. No. 6,284,275; U.S. Pat. No. 6,485,748; U.S. Pat. No. 6,495,162; U.S. Pat. No. 6,524,620; U.S. Pat. No. 6,544,556; U.S. Pat. No. 6,589,553; U.S. Pat. No. 6,602,522; and U.S. Pat. No. 6,610,326.
Examples of controlled release formulations, tablets, dosage forms, and drug delivery systems that are suitable for use with the present invention are described in the following published US and PCT patent applications assigned to Andrx Corporation: US20010024659; US20020115718; US20020156066; WO0004883; WO0009091; WO0012097; WO0027370; WO0050010; WO0132161; WO0134123; WO0236077; WO0236100; WO02062299; WO02062824; WO02065991; WO02069888; WO02074285; WO03000177; WO9521607; WO9629992; WO9633700; WO9640080; WO9748386; WO9833488; WO9833489; WO9930692; WO9947125; and WO9961005.
Some other examples of drug delivery approaches focus on non-oral drug delivery, providing parenteral, transmucosal, and topical delivery of proteins, peptides, and small molecules. For example, the Atrigel® drug delivery system marketed by Atrix Laboratories Inc. comprises biodegradable polymers, similar to those used in biodegradable sutures, dissolved in biocompatible carriers. These pharmaceuticals may be blended into a liquid delivery system at the time of manufacturing or, depending upon the product, may be added later by a physician at the time of use. Injection of the liquid product subcutaneously or intramuscularly through a small gauge needle, or placement into accessible tissue sites through a cannula, causes displacement of the carrier with water in the tissue fluids, and a subsequent precipitate to form from the polymer into a solid film or implant. The drug encapsulated within the implant is then released in a controlled manner as the polymer matrix biodegrades over a period ranging from days to months. Examples of such drug delivery systems include Atrix's Eligard®, Atridox®/Doxirobe®, Atrisorb® FreeFlow™/Atrisorb®-D FreeFlow, bone growth products, and others as described in the following published US and PCT patent applications assigned to Atrix Laboratories Inc.: U.S. Pat. No. RE37950; U.S. Pat. No. 6,630,155; U.S. Pat. No. 6,566,144; U.S. Pat. No. 6,610,252; U.S. Pat. No. 6,565,874; U.S. Pat. No. 6,528,080; U.S. Pat. No. 6,461,631; U.S. Pat. No. 6,395,293; U.S. Pat. No. 6,261,583; U.S. Pat. No. 6,143,314; U.S. Pat. No. 6,120,789; U.S. Pat. No. 6,071,530; U.S. Pat. No. 5,990,194; U.S. Pat. No. 5,945,115; U.S. Pat. No. 5,888,533; U.S. Pat. No. 5,792,469; U.S. Pat. No. 5,780,044; U.S. Pat. No. 5,759,563; U.S. Pat. No. 5,744,153; U.S. Pat. No. 5,739,176; U.S. Pat. No. 5,736,152; U.S. Pat. No. 5,733,950; U.S. Pat. No. 5,702,716; U.S. Pat. No. 5,681,873; U.S. Pat. No. 5,660,849; U.S. Pat. No. 5,599,552; U.S. Pat. No. 5,487,897; U.S. Pat. No. 5,368,859; U.S. Pat. No. 5,340,849; U.S. Pat. No. 5,324,519; U.S. Pat. No. 5,278,202; U.S. Pat. No. 5,278,201; US20020114737, US20030195489; US20030133964; US 20010042317; US20020090398; US20020001608; and US2001042317.
Atrix Laboratories Inc. also markets technology for the non-oral transmucosal delivery of drugs over a time period from minutes to hours. For example, Atrix's BEMA™ (Bioerodible Muco-Adhesive Disc) drug delivery system comprises pre-formed bioerodible discs for local or systemic delivery. Examples of such drug delivery systems include those as described in U.S. Pat. No. 6,245,345.
Other drug delivery systems marketed by Atrix Laboratories Inc. focus on topical drug delivery. For example, SMP™ (Solvent Particle System) allows the topical delivery of highly water-insoluble drugs. This product allows for a controlled amount of a dissolved drug to permeate the epidermal layer of the skin by combining the dissolved drug with a microparticle suspension of the drug. The SMP™ system works in stages whereby: 1) the product is applied to the skin surface; 2) the product near follicles concentrates at the skin pore; 3) the drug readily partitions into skin oils; and 4) the drug diffuses throughout the area. By contrast, MCA® (Mucocutaneous Absorption System) is a water-resistant topical gel providing sustained drug delivery. MCA® forms a tenacious film for either wet or dry surfaces where: 1) the product is applied to the skin or mucosal surface; 2) the product forms a tenacious moisture-resistant film; and 3) the adhered film provides sustained release of drug for a period from hours to days. Yet another product, BCP™ (Biocompatible Polymer System) provides a non-cytotoxic gel or liquid that is applied as a protective film for wound healing. Examples of these systems include Orajel®-Ultra Mouth Sore Medicine as well as those as described in the following published US patents and applications assigned to Atrix Laboratories Inc.: U.S. Pat. No. 6,537,565; U.S. Pat. No. 6,432,415; U.S. Pat. No. 6,355,657; U.S. Pat. No. 5,962,006; U.S. Pat. No. 5,725,491; U.S. Pat. No. 5,722,950; U.S. Pat. No. 5,717,030; U.S. Pat. No. 5,707,647; U.S. Pat. No. 5,632,727; and US20010033853.
Additional formulations and compositions available from Teva Pharmaceutical Industries Ltd., Warner Lambert & Co., and Godecke Aktiengesellshaft that include gabapentin and are useful in the present invention include those as described in the following US patents and published US and PCT patent applications: U.S. Pat. No. 6,531,509; U.S. Pat. No. 6,255,526; U.S. Pat. No. 6,054,482; US2003055109; US2002045662; US2002009115; WO 01/97782; WO 01/97612; EP 2001946364; WO 99/59573; and WO 99/59572.
Additional formulations and compositions that include oxybutynin and are useful in the present invention include those as described in the following US patents and published US and PCT patent applications: U.S. Pat. No. 5,834,010; U.S. Pat. No. 5,601,839; and U.S. Pat. No. 5,164,190.
Dosage and Administration
The concentration of the active agent in any of the aforementioned dosage forms and compositions can vary a great deal, and will depend on a variety of factors, including the type of composition or dosage form, the corresponding mode of administration, the nature and activity of the specific active agent, and the intended drug release profile. Preferred dosage forms contain a unit dose of active agent, i.e., a single therapeutically effective dose. For creams, ointments, etc., a “unit dose” requires an active agent concentration that provides a unit dose in a specified quantity of the formulation to be applied. The unit dose of any particular active agent will depend, of course, on the active agent and on the mode of administration.
For the active agents of the present invention (including an α2δ subunit calcium channel modulator in combination with a compound with smooth muscle modulatory effects), the unit dose for oral, transmucosal, topical, transdermal, and parenteral administration will be in the range of from about 1 ng to about 10,000 mg, about 5 ng to about 9,500 mg, about 10 ng to about 9,000 mg, about 20 ng to about 8,500 mg, about 30 ng to about 7,500 mg, about 40 ng to about 7,000 mg, about 50 ng to about 6,500 mg, about 100 ng to about 6,000 mg, about 200 ng to about 5,500 mg, about 300 ng to about 5,000 mg, about 400 ng to about 4,500 mg, about 500 ng to about 4,000 mg, about 1 μg to about 3,500 mg, about 5 μg to about 3,000 mg, about 10 μg to about 2,600 mg, about 20 μg to about 2,575 mg, about 30 μg to about 2,550 mg, about 40 μg to about 2,500 mg, about 50 μg to about 2,475 mg, about 100 μg to about 2,450 mg, about 200 μg to about 2,425 mg, about 300 μg to about 2,000, about 400 μg to about 1,175 mg, about 500 μg to about 1,150 mg, about 0.5 mg to about 1,125 mg, about 1 mg to about 1,100 mg, about 1.25 mg to about 1,075 mg, about 1.5 mg to about 1,050 mg, about 2.0 mg to about 1,025 mg, about 2.5 mg to 1,000 mg, about 3.0 mg to about 975 mg, about 3.5 mg to about 950 mg, about 4.0 mg to about 925 mg, about 4.5 mg to about 900 mg, about 5 mg to about 875 mg, about 10 mg to about 850 mg, about 20 mg to about 825 mg, about 30 mg to about 800 mg, about 40 mg to about 775 mg, about 50 mg to about 750 mg, about 100 mg to about 725 mg, about 200 mg to about 700 mg, about 300 mg to about 675 mg, about 400 mg to about 650 mg, about 500 mg, or about 525 mg to about 625 mg.
Alternatively, for active agents of the present invention (including an α26 subunit calcium channel modulator in combination with a compound with smooth muscle modulatory effects), the unit dose for oral, transmucosal, topical, transdermal, and parenteral administration will be equal to or greater than about 1 ng, about 5 ng, about 10 ng, about 20 ng, about 30 ng, about 40 ng, about 50 ng, about 100 ng, about 200 ng, about 300 ng, about 400 ng, about 500 ng, about 1 Ag, about 5 μg, about 10 μg, about 20 μg, about 30 μg, about 40 μg, about 50 μg, about 100 μg, about 200 μg, about 300 μg, about 400 μg, about 500 μg, about 0.5 mg, about 1 mg, about 1.25 mg, about 1.5 mg, about 2.0 mg, about 2.5 mg, about 3.0 mg, about 3.5 mg, about 4.0 mg, about 4.5 mg, about 5 mg, about 10 mg, about 20 mg, about 30 mg, about 40 mg, about 50 mg, about 100 mg, about 200 mg, about 300 mg, about 400 mg, about 500 mg, about 600 mg, about 625 mg, about 650 mg, about 675 mg, about 700 mg, about 725 mg, about 750 mg, about 775 mg, about 800 mg, about 825 mg, about 850 mg, about 875 mg, about 900 mg, about 925 mg, about 950 mg, about 975 mg, about 1000 mg, about 1025 mg, about 1050 mg, about 1075 mg, about 1100 mg, about 1125 mg, about 1150 mg, about 1175 mg, about 1200 mg, about 1225 mg, about 1250 mg, about 1275 mg, about 1300 mg, about 1325 mg, about 1350 mg, about 1375 mg, about 1400 mg, about 1425 mg, about 1450 mg, about 1475 mg, about 1500 mg, about 1525 mg, about 1550 mg, about 1575 mg, about 1606 mg, about 1625 mg, about 1650 mg, about 1675 mg, about 1700 mg, about 1725 mg, about 1750 mg, about 1775 mg, about 1800 mg, about 1825 mg, about 1850 mg, about 1875 mg, about 1900 mg, about 1925 mg, about 1950 mg, about 1975 mg, about 2000 mg, about 2025 mg, about 2050 mg, about 2075 mg, about 2100 mg, about 2125 mg, about 2150 mg, about 2175 mg, about 2200 mg, about 2225 mg, about 2250 mg, about 2275 mg, about 2300 mg, about 2325 mg, about 2350 mg, about 2375 mg, about 2400 mg, about 2425 mg, about 2450 mg, about 2475 mg, about 2500 mg, about 2525 mg, about 2550 mg, about 2575 mg, about 2600 mg, about 3,000 mg, about 3,500 mg, about 4,000 mg, about 4,500 mg, about 5,000 mg, about 5,500 mg, about 6,000 mg, about 6,500 mg, about 7,000 mg, about 7,500 mg, about 8,000 mg, about 8,500 mg, about 9,000 mg, or about 9,500 mg.
For the active agents of the present invention (including an α2δ subunit calcium channel modulator in combination with a compound with smooth muscle modulatory effects), the unit dose for intrathecal administration will be in the range of from about 1 fg to about 1 mg, about 5 fg to about 500 μg, about 10 fg to about 400 μg, about 20 fg to about 300 μg, about 30 fg to about 200 μg, about 40 fg to about 100 μg, about 50 fg to about 50 μg, about 100 fg to about 40 μg, about 200 fg to about 30 μg, about 300 fg to about 20 μg, about 400 fg to about 10 μg, about 500 fg to about 5 μg, about 1 μg to about 1 μg, about 5 μg to about 500 ng, about 10 μg to about 400 ng, about 20 μg to about 300 ng, about 30 μg to about 200 ng, about 40 μg to about 100 ng, about 50 μg to about 50 ng, about 100 μg to about 40 ng, about 200 μg to about 30 ng, about 300 μg to about 20 ng, about 400 μg to about 10 ng, about 500 μg to about 5 ng,
Alternatively, for the active agents of the present invention (including an α2δ subunit calcium channel modulator in combination with a compound with smooth muscle modulatory effects), the unit dose for intrathecal administration will be equal to or greater than about 1 fg, about 5 fg, about 10 fg, about 20 fg, about 30 fg, about 40 fg, about 50 fg, about 100 fg, about 200 fg, about 300 fg, about 400 fg, about 500 fg, about 1 pg, about 5 pg, about 10 pg, about 20 pg, about 30 pg, about 40 pg, about 50 pg, about 100 pg, about 200 pg, about 300 pg, about 400 pg, about 500 pg, about 1 ng, about 5 ng, about 10 ng, about 20 ng, about 30 ng, about 40 ng, about 50 ng, about 100 ng, about 200 ng, about 300 ng, about 400 ng, about 500 ng, about 1 μg, about 5 μg, about 10 μg, about 20 μg, about 30 μg, about 40 μg, about 50 μg, about 100 μg, about 200 μg, about 300 μg, about 400 μg, or about 500 μg.
The present invention also encompasses a pharmaceutical formulation encompassing oxybutyinin, wherein the unit dose for oral, transmucosal, topical, transdermal, and parenteral administration of said oxybutynin will be in an amount equal to or less than about 5 mg, about 4.5 mg, about 4 mg, about 3.5 mg, about 3 mg, about 2.5 mg, about 2 mg, about 1.5 mg, about 1.25 mg, about 1.0 mg, or about 0.5 mg. Because of the synergistic action of α2δ subunit calcium channel modulators when combined with smooth muscle modulators, dosages of α2δ subunit calcium channel modulators and smooth muscle modulators that have been known in the art or predicted not to be effective for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, as well as pain associated with specific disorders such as interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome are effective when administered according to the methods of the present invention.
A therapeutically effective amount of a particular active agent administered to a given individual will, of course, be dependent on a number of factors, including the concentration of the specific active agent, composition or dosage form, the selected mode of administration, the age and general condition of the individual being treated, the sex of the individual, the severity of the individual's condition, and other factors known to the prescribing physician.
In a preferred embodiment, drug administration is on an as-needed basis, and does not involve chronic drug administration. With an immediate release dosage form, as-needed administration may involve drug administration immediately prior to commencement of an activity wherein suppression of pain would be desirable, but will generally be in the range of from about 0 minutes to about 10 hours prior to such an activity, preferably in the range of from about 0 minutes to about 5 hours prior to such an activity, most preferably in the range of from about 0 minutes to about 3 hours prior to such an activity. With a sustained release dosage form, a single dose can provide therapeutic efficacy over an extended time period in the range of from about 1 hour to about 72 hours, typically in the range of from about 8 hours to about 48 hours, depending on the formulation. That is, the release period may be varied by the selection and relative quantity of particular sustained release polymers. If necessary, however, drug administration may be carried out within the context of an ongoing dosage regimen, i.e., on a weekly basis, twice weekly, daily, etc.
In another preferred embodiment, at least one detrimental side effect associated with single administration of an α2δ calcium channel modulator or a smooth muscle modulator is lessened by concurrent administration of an α2δ subunit calcium channel modulator with a smooth muscle modulator. For example, side effects for oxybutynin, an antimuscarinic smooth muscle modulator, include dry mouth, sensitivity to bright light, blurred vision, dry eyes, decreased sweating, flushing, upset stomach, constipation, and drowsiness. However, when administered in combination with an α2δ subunit calcium channel modulator such as gabapentin, significantly less of each agent is needed to achieve therapeutic efficacy (e.g., less than the 5 mg dose of oxybutynin currently marketed in the United States and also less than the 2.5 mg dose of oxybutynin currently marketed in Europe). Because detrimental side effects are lessened, the present invention also has the benefit of improving patient compliance.
Packaged Kits
In another embodiment, a packaged kit is provided that contains the pharmaceutical formulation to be administered, i.e., a pharmaceutical formulation containing a therapeutically effective amount of an α2δ subunit calcium channel modulator in combination with one or more compounds with smooth muscle modulatory effects for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome, a container, preferably sealed, for housing the formulation during storage and prior to use, and instructions for carrying out drug administration in a manner effective for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. The instructions will typically be written instructions on a package insert and/or on a label. Depending on the type of formulation and the intended mode of administration, the kit may also include a device for administering the formulation. Formulations may be any suitable formulations as described herein. For example, formulations may be an oral dosage form containing a unit dosage of a selected active agent.
The kit may contain multiple formulations of different dosages of the same agent. The kit may also contain multiple formulations of different active agents. The kit may contain formulations suitable for sequential, separate and/or simultaneous use in treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome, and instructions for carrying out drug administration where the formulations are administered sequentially, separately and/or simultaneously in treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome.
The kit may also contain at least one component selected from an α2δ subunit calcium channel modulator and a smooth muscle modulator; a container housing said component or components during storage and prior to administration; and instructions for carrying out drug administration of an α2δ subunit calcium channel modulator with a smooth muscle modulator in a manner effective to treat pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. Such a kit may be useful, for example, where the α2δ subunit calcium channel modulator or the smooth muscle modulator is already being administered to the patient, and the additional component is to be added to the patient's drug regimen. Such a kit may also be useful where different individuals (e.g., physicians or other medical professionals) are administering the separate components of the combination of the present invention,
The parts of the kit may be independently held in one or more containers—such as bottles, syringes, plates, wells, blister packs, or any other type of pharmaceutical packaging.
Insurance Claims
In general, the processing of an insurance claim for the coverage of a given medical treatment or drug therapy involves notification of the insurance company, or any other entity, that has issued the insurance policy against which the claim is being filed, that the medical treatment or drug therapy will be performed. A determination is then made as to whether the medical treatment or drug therapy that will be performed is covered under the terms of the policy. If covered, the claim is then processed, which can include payment, reimbursement, or application against a deductable.
The present invention encompasses a method for processing an insurance claim under an insurance policy for the treatment of pain using a compound with smooth muscle modulatory effects in combination with an α2δ subunit calcium channel modulator or pharmaceutically acceptable salts, esters, amides, prodrugs, or active metabolites thereof, wherein said combination of α2δ subunit calcium channel modulator and compound with smooth muscle modulatory effects or pharmaceutically acceptable salts, esters, amides, prodrugs, or active metabolites thereof are administered sequentially or concurrently in different compositions. This method comprises: 1) receiving notification that treatment using said compound with smooth muscle modulatory effects in combination with an α2δ subunit calcium channel modulator or pharmaceutically acceptable salts, esters, amides, prodrugs or active metabolites thereof will be performed or notification of a prescription; 2) determining whether said treatment using said compound with smooth muscle modulatory effects in combination with an α2δ subunit calcium channel modulator or pharmaceutically acceptable salts, esters, amides, prodrugs or active metabolites is covered under said insurance policy; and 3) processing said claim for treatment of pain using said compound with smooth muscle modulatory effects in combination with an α2δ subunit calcium channel modulator or pharmaceutically acceptable salts, esters, amides, prodrugs, or active metabolites thereof, including payment, reimbursement, or application against a deductable. For use in this method, a particularly preferred α2δ subunit calcium channel modulator is gabapentin, while a particularly preferred compound with smooth muscle modulatory effects is oxybutynin. This method also encompasses the processing of claims for an α2δ subunit calcium channel modulator, particularly gabapentin, or a compound with smooth muscle modulatory effects, particularly oxybutynin, when either has been prescribed separately or concurrently for the treatment of pain.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended embodiments. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Methods for Treating Pain Using α2δ Subunit Calcium Channel Modulators With Smooth Muscle Modulators
The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims. The following examples illustrate the effects of administration of a α2δ subunit calcium channel modulator, particularly gabapentin, with a compound with smooth muscle modulatory effects, particularly oxybutynin, on well-accepted models for pain. In each of these examples, a combination of α2δ subunit calcium channel modulator and compound with smooth muscle modulatory effects may be administered by any route of administration, including orally, intraduodenally, intravenously, subcuteaneously, intraperitoneally, intrathecally, intradermally, and transdermally. These models can be utilized to assess whether administration of said combination before insult can prevent pain, or if administration of said combination after insult can stop pain. It is expected that these results will demonstrate the efficacy of the combination of an α2δ subunit calcium channel modulator with a compound with smooth muscle modulatory effects for treatment of pain.
These methods include the use of well-accepted models for pain, including the spinal nerve ligation model of Kim and Chung (1992) Pain 50:355-363, the sciatic nerve ligation model of Bennett and Xie (1988) Pain 33:87-107, the carageenan-induced thermal analgesia model of Winter et al. (1962) Proc. Soc. Exp. Bio. & Med., 111: 554; the formalin pain model of Doak et al. (1995) Eur. J. Pharmacol. 281:311; the somatic pain models of Jarvis et al. (2002) Proc. Natl. Acad. Sci. USA 99:17179-17184; the plantar incision model of Brennan et al (1996) Pain 64:493-501; the abdominal pain constriction model of Collier et al. 1968 Br. J. Pharmacol. 32:295-310; the noxious colonic distension model of Jarvis et al. (2002) Proc. Natl. Acad. Sci. USA 99:17179-17184; and irritative models using intravesically administered acetic acid as described in Sasaki et al. (2002) J. Urol. 168: 1259-64 and Thor and Katofiasc (1995) J. Pharmacol. Exptl. Ther. 274: 1014-24.
Rats are divided into two groups, one receiving a L5/L6 spinal ligation as described in Kim and Chung (1992) Pain 50:355-363 and the other receiving a sham surgery. Briefly, rats are anesthetized with halothane and the vertebrae over the L4 to S2 region are exposed. The L5 and L6 spinal nerves are exposed, carefully isolated, and tightly ligated with 4-0 silk suture distal to the dorsal root ganglion (“DRG”). After ensuring homeostatic stability, the wounds are sutured, and the rats allowed to recover in individual cages. Sham-operated rats are prepared in an identical manner except that the L5 and L6 spinal nerves are not ligated. Rats are tested for the effects of drugs on nociception 10-14 days later. Any rats which show signs of motor deficiency are not used in the study.
The control or combination gabapentin and oxybutynin are administered at a pre-determined time point following the surgeries. Allodynia and thermal hyperalgesia are respectively measured with Von Frey filaments and tail-or paw-flick with a radiant heat source. The allodynia and thermal hyperalgesia measurements are performed at the following time points-prior to surgery, following surgery but prior to the administration of control or combination gabapentin and oxybutynin, and following surgery after the administration of control or combination gabapentin and oxybutynin.
Mechanical allodynia is determined in the manner described by Chaplan et al. (1994) J. Neurosci. Methods 53(1):55-63, wherein the paw withdrawal threshold is determined in response to probing with calibrated von Frey filaments. In this method, the rats are suspended in cages having wire mesh floors. Von Frey filaments are applied perpendicularly to the plantar surface of the rat's paw until it buckles slightly, and is held for about 3 to 6 seconds. A positive response is indicated by a sharp or abrupt withdrawal of the paw. The 50% paw withdrawal threshold is determined by a non-parametric method, as is well known to those skilled in the art.
Thermal hyperalgesia is determined by focusing a radiant heat source onto the plantar surface of the affected paw of nerve-ligated or sham-operated rats. When a rat withdraws its paw, a photodetection devices halts the stimulus and the timer. A maximal cut-off time of 40 seconds is used to prevent tissue damage. Paw withdrawal latencies are thus determined to the nearest 0.1 second. The withdrawal latency of sham-operated rats is compared to those of nerve-ligated rats to measure the degree of hyperalgesia.
Preparation of the rat pain model based on the constriction of the sciatic nerve is performed by the method introduced by Bennett and Xie (1988) Pain 33:87-107. Briefly, the rat is anesthetized with i.p. injection of pentobarbital sodium at 40 mg/kg; the overlying skin is cut open; and the left biceps femoris muscle is bluntly separated. The sciatic nerve is isolated from surrounding tissues; it is gently constricted at four sites about 1 mm apart from each other by the use of surgical chromic gut sutures (4-0); the operated part is closed; and the rat is returned to its cage for further feeding. For the rat belonging to the sham-surgery group, the same operation is performed except that the sciatic nerve is left untouched. Two weeks after the surgery, the response threshold to a mechanical stimulus consisting of touch with a von Frey filament is determined as follows: the combination is administered to the rat having the sciatic nerve constricted; one hour later, von Frey hairs are applied against the foot pad (spots ranging from heel to the mid-point of foot) one after another in an ascending order of their stiffness; if the rat raises its foot when a certain von Frey hair is applied, the stimulus intensity of that hair is taken as the response threshold (maximum stimulus intensity being 28.84 g).
To investigate whether combination gabapentin and oxybutynin mediates hyperalgesia induced by inflammatory agents, rats receive intradermal 100 μl injections of a 1% solution of λ-carrageenan or saline. Three and a half hours later, the rats receive no treatment or of sterile water followed by combination gabapentin and oxybutynin or control. Mechanical stimuli are applied 30 minutes later, and rats are observed for hyperalgesia using the Randall-Selitto paw-withdrawal test.
Methods essentially as disclosed by Doak et al. (1995) Eur. J. Pharmacol. 281:311 are used to determine the effect of combination gabapentin and oxybutynin for the treatment of pain. Specifically, 25 μL of 0.5% formalin solution is subcutaneously injected into the left foot pad of the rat. The combination gabapentin and oxybutynin is administered to the rat 30 minutes before the subcutaneous injection of formalin. Rats are observed for nociceptive behavior, including flinching, licking or biting the injected paw. Such behavior is timed for its duration, and the cumulative duration is recorded at five minute intervals. The nociceptive response observed within 10 minutes after the injection is termed a first-phase response, while the response observed between 10 minutes and 45 minutes after the injection is termed a second-phase response. The inhibitory effect of the combination gabapentin and oxybutynin on the nociceptive response induced by the formalin injection is calculated according to the following formula:
Percent inhibition (%)-[(PRcontrol-PRtest)/PRcontrol].×.100
wherein PRtest is the response time (sec) of the test group which receives formalin and the combination gabapentin and oxybutynin, while PRcontol is the response time of the control group which receives formalin alone.
Rats are treated with combination gabapentin and oxybutynin or control and tested for their response to acute somatic pain using models essentially as described in Jarvis et al. (2002) Proc. Natl. Acad. Sci. USA 99:17179-17184.
Briefly, the response to mechanical stimulation is measured using the Ugo Basile analgesymeter (Comerio, Italy). In this model, rats are restrained while steadily increasing pressure is applied to the dorsal surface of a hind paw via a dome-shaped plastic tip. The pressure at which the paw is withdrawn is recorded.
The response to acute thermal stimulation is determined using a paw thermal stimulator (UARDG, University of California, San Diego). Rats are allowed to habituate in Plexiglas cubicles maintained at 30° C. A thermal stimulus is applied to the plantar surface of each hindpaw. Pain withdrawal tendencies are calculated as the mean of three sequential trials.
Analgesia is measured using a hotplate assay. Mice are placed on the hotplate in individual enclosures and the latency until the 10th jump is recorded by disruption of a photocell beam located 12.5 cm above the surface of the hotplate. Mice are removed after the earliest of either 10 jumps or 180 seconds, and the latency until the 10th jump is used for statistical analysis.
The Plantar Incision Model is performed essentially as described in Brennan et al. (1996) Pain 64:493-501. Briefly, a 1-cm longitudinal incision is made through skin, fascia and muscle of the plantar aspect of the foot in anesthetized rats. Animals are tested for mechanical allodynia using von Frey filaments before surgery and for 6 days afterwards. Animals are then administered combination gabapentin and oxybutynin or control. A cumulative pain score based on the weight-bearing behavior of the animals is also utilized.
The modified test of Collier et al. 1968 Br. J: Pharmacol. 32:295-310, as described by Jarvis et al. (2002) Proc. Natl. Acad. Sci. USA 99:17179-17184 is used. Briefly, animals are administered combination gabapentin and oxybutynin or control prior to injection with 0.3 ml of 0.6% acetic acid in saline to evoke writhing. The number of abdominal constrictions is recorded from 5 to 20 min. after injection of acetic acid. Control animals are compared to treated animals for differences.
The colorectal distension model as described Jarvis et al. (2002) Proc. Natl. Acad. Sci. USA 99:17179-17184 is used to determine the efficacy of combination gabapentin and oxybutynin for treating visceral pain. Briefly, a latex balloon tied to Tygon tubing is inserted intra-anally until the end of the balloon is 1 cm inside the rectum. The electromyogram signal is recorded during phasic distentions and activity is quantified. Three distentions are performed to establish a baseline response magnitude. Subsequently, the animals are anesthetized with halothane, and 1 ml zymosan (25 mg/ml in 30% ethanol) is introduced into the distal colon. Three hours after the introduction of zymosan, three phasic distentions are repeated to evaluate hyperalgesia. Immediately, combination gabapentin and oxybutynin or control is administered. Thirty minutes later, three phasic distensions are repeated to determine the efficacy of combination gabapentin and oxybutynin for the treatment of visceral pain.
Objective and Rationale
The objective of this study was to determine the ability of an α2δ subunit calcium channel modulator in combination with a smooth muscle modulator to reverse the reduction in bladder capacity seen following continuous infusion of dilute acetic acid, an irritative model. In particular, the current study utilized gabapentin as an exemplary α2δ subunit calcium channel modulator, and oxybutynin as an exemplary a smooth muscle modulator.
Materials and Methods
Urethane anesthetized (1.2 g/kg) normal female rats were utilized in this study. Groups of rats were treated with oxybutynin alone (n=13), gabapentin alone (n=11), and respective dose-matched combinations of oxybutynin and gabapentin (n=11). Subsequently, three series at markedly lower doses and at different dose ratios were performed for the purposes of isobologram construction (n=4/group). Cumulative dose-response protocols were utilized with half log increments for all studies.
Drugs and Preparation
Drugs were dissolved in normal saline at 1, 3 and 10 mg/ml for oxybutynin and 30, 100 and 300 mg/ml for gabapentin. In these studies, individual doses and combinations may be subsequently referred to as Low, Mid and High.
Subsequent studies aimed at isobologram construction combined the drugs in dose combinations as shown in the table below (low, middle and high doses for each drug paired). Animals were dosed by volume of injection=body weight in kg.
Acute Anesthetized In Vivo Model
Animal Preparation: Female rats (250-300 g body weight) were anesthetized with urethane (1.2 g/kg) and a saline-filled catheter (PE-50) was inserted into the jugular vein for intravenous drug administration. Via a midline lower abdominal incision, a flared-tipped PE 50 catheter was inserted into the bladder dome for bladder filling and pressure recording. The abdominal cavity was moistened with saline and closed by covering with a thin plastic sheet in order to maintain access to the bladder for emptying purposes. Fine silver or stainless steel wire electrodes were inserted into the external urethral sphincter (EUS) percutaneously for electromyography (EMG).
Experimental Design: Saline was continuously infused at a rate of 0.055 ml/min via the bladder-filling catheter for 60 minutes to obtain a baseline of lower urinary tract activity (continuous cystometry; CMG). Following the control period, a 0.25% acetic acid solution in saline was infused into the bladder at the same flow rate to induce bladder irritation. Following 30 minutes of AA infusion, 3 vehicle injections were made at 20 minute intervals to determine vehicle effects, if any. Subsequently, increasing doses of a selected active agent, or combination of agents, at half log increments were administered intravenously at 30 minute intervals in order to construct a cumulative dose-response relationship. At the end of the control saline cystometry period, the third vehicle, and 20 minutes following each subsequent treatment, the infusion pump was stopped, the bladder was emptied by fluid withdrawal via the infusion catheter and a single filling cystometrogram was performed at the same flow rate in order to determine changes in bladder capacity caused by the irritation protocol and subsequent intravenous drug administration.
Data Analysis
Bladder capacity data for each animal were normalized to “% Recovery from Irritation,” and this index was used as the measure of efficacy. Data from experiments in which each of the drugs were administered alone were utilized to create theoretical populations of additive effects for each dose (low, mid and high), and these were compared by one-tailed t-test (individual dose comparisons) and by 2-Way ANOVA (across doses) to the actual combination drug data. The means and standard deviations of each individual treatment's “dose-matched” (low, middle, and high) responses were added together to estimate the mean and standard deviation of the theoretical additive populations for which to compare to the actual data obtained from the combination experiments. The theoretical additive effect population N=(Nantimuscarinic+Nα28 subunit modulator)−1. P<0.050 was considered significant. Only rats that showed between a 50-90% reduction in bladder capacity at the third vehicle measurement when compared to pre-irritation saline control values were utilized for numerical analyses.
Isobologram construction consisted of two methods, both utilizing the same data, but plotting the results either as group means or by individual responses. When utilizing group mean data, the common maximal effect reached by both drugs alone and the combinations listed in the above table was a return to 43% of saline control bladder capacity values. When utilizing individual responses for both drugs alone and the combinations listed in the above table, the target value was 31% of saline control. These low values reflect the modest effectiveness of oxybutynin and gabapentin alone. For statistical purposes, the data were analyzed making comparisons for each drug, regardless of whether alone or in combination.
Results and Conclusions
The effect of cumulative increasing doses of oxybutynin (n=13), gabapentin (n=11) and their matched combinations (e.g. Dose 1 for the combination was 30 mg/kg gabapentin and 1 mg/kg oxybutynin; n=11) on bladder capacity is depicted in
The effect of cumulative increasing doses of oxybutynin (n=13), gabapentin (n=11) and their matched combinations (e.g. Dose 1 for the combination was 30 mg/kg gabapentin and 1 mg/kg oxybutynin; n=11) on bladder capacity (normalized to % Recovery from Irritation) is depicted in
Results of the isobologram studies as determined by utilizing group means to determine effective doses is depicted in
A common maximal effect of individual animals was determined (a return to 31% of saline control values;
The ability of an α2δ subunit calcium channel modulator in combination with a smooth muscle modulator to produce a dramatic reversal in acetic acid irritation-induced reduction in bladder capacity strongly indicates efficacy for treating pain, including neuropathic pain, nociceptive pain, chronic pelvic pain, and pain associated with specific disorders including interstitial cystitis, prostatitis, prostadynia, vulvar vestibulitis, vulvodynia, functional abdominal pain syndrome, functional dyspepsia, and irritable bowel syndrome. Furthermore, the combination of an α2δ subunit calcium channel modulator and a smooth muscle modulator produced a synergistic effect that was greater than what would be expected if the effects were simply additive, and also demonstrated efficacy using amounts of the individual agents that are much lower than would be expected to produce an effect if the agents were administered singly.
Objective and Rationale
The purpose of this study was to determine concentrations of gabapentin, oxybutynin and desethyl oxybutynin in rat plasma samples over a 2 hour period following either 3 mg/kg oxybutynin, 100 mg/kg gabapentin, or the combination of those 2 drugs at those doses using a liquid chromatography with tandem mass spectrometric detection (LC/MS/MS) method.
Materials and Methods
Urethane anesthetized (1.2 g/kg) normal female rats were utilized in this study. Groups of rats were treated with oxybutynin alone (n=6), gabapentin alone (n=8), and respective dose-matched combinations of oxybutynin and gabapentin (n=8).
Drugs and Preparation
Drugs were dissolved in normal saline at 3 mg/ml for oxybutynin and 100 mg/ml for gabapentin. Animals were dosed by volume of injection=body weight in kg.
Pharmacokinetic In Vivo Preparation
Animal Preparation: Female rats (250-300 g body weight) were anesthetized with urethane (1.2 g/kg) and a saline-filled catheter (PE-50) was inserted into the jugular vein for intravenous drug administration.
Experimental Design: Plasma samples (200 μl; K3 EDTA) were taken on ice at 4 time points (15, 30 60 and 120 minutes) following intravenous drug administration. Samples were spun at 1600 RPM for 7 minutes, plasma was drawn off and stored at −80 C until chromatographic analysis.
Pharmacokinetic Chromatographic Analysis
Internal Standards: Oxybutynin-D11 chloride and baclofen were used as internal standards.
All stock solutions and working internal standard were stored at 2-8° C. Initial standard was stored frozen at approxinatrely −20° C.
Calculations: Calculations were performed using Excel Version 8.0e. Some reported values may differ in the last reported digit from values calculated directly from the report tables due to the rounding that has been applied.
Pharmacokinetic Analysis: The maximum concentration (Cmax) in rat plasma and the time to reach maximum concentration (Tmax) were obtained by visual inspection of the raw data. Pharmacokinetic parameters calculated included half-life (t1/2), time to maximum plasma concentration (Tmax), area under the concentration-time curve from time 0 to the last time point (AUC0-t), area under the concentration-time curve from 0 to infinity (AUC0-∞), volume of distribution (Vz) and clearance (CL). Pharmacokinetic parameters were calculated by using WinNonlin Professional Edition (Pharsight Corporation, Version 3.3).
Results and Conclusions
For gabapentin (Table 2), the elimination phase of the concentration vs. time profiles was not well defined. Based on the comparison of Cmax and AUC0-T data, there appeared to be no appreciable difference between the oxybutynin (Oxy) group and the combination (Com) group. No evidence of drug-drug interaction between oxybutynin and gabapentin was found with the current study design.
For oxybutynin (Table 3), the pharmacokinetic parameters (Cmax, AUC0-t, AUC0-∞, t1/2, Vz and CL) obtained from the combination (Com) group did not appear to be appreciably different than those from the oxybutynin (Oxy) group. No evidence of drug-drug interaction between oxybutynin and gabapentin was found with the current study design.
For desethyl oxybutynin (Table 4), the elimination phase of the concentration vs. time profile was not well defined. However, based on the comparison of Cmax, and AUC0-t data, there again appeared to be no appreciable difference between the oxybutynin (Oxy) group and the combination (Com) group.
The results of the pharmacokinetic study indicate that pharmacokinetic influences of one drug on the other do not account for the synergistic nature of the oxybutynin-gabapentin combination as seen in Example 9. That is to say that the synergistic nature of the positive effect of the combination in an irritative model is not due to some pharmacokinetic interaction.
AUC0-∞ Area under the plasma concentration-time curve up to infinity.
AUC0-t Area under the plasma concentration-time curve up to the last sampling time with measurable concentrations.
CL Clearance.
Cmax Maximum plasma concentration.
NA Not applicable.
NC Not calculated due to insufficient elimination phase data.
SD Standard deviation.
t1/2 Observed elimination half-life.
Tmax Time to maximum concentration.
Vz Volume of distribution.
*Outliers. Excluded from mean and SD calculations.
AUC0-∞ Area under the plasma concentration-time curve up to infinity.
AUC0-t Area under the plasma concentration-time curve up to the last sampling time with measurable concentrations.
CL Clearance.
Cmax Maximum plasma concentration.
NA Not applicable.
NC Not calculated due to insufficient elimination phase data.
SD Standard deviation.
t1/2 Observed elimination half-life.
Tmax Time to maximum concentration.
Vz Volume of distribution.
AUC0-∞ Area under the plasma concentration-time curve up to infinity.
AUC0-t Area under the plasma concentration-time curve up to the last sampling time with measurable concentrations.
CL Clearance.
Cmax Maximum plasma concentration.
NA Not applicable.
NC Not calculated due to insufficient elimination phase data.
SD Standard deviation.
t1/2 Observed elimination half-life.
Tmax Time to maximum concentration.
Vz Volume of distribution.
All publications and patent applications mentioned in the specification are indicative of the level of those skilled in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US04/08700 | 3/22/2004 | WO | 6/23/2006 |
| Number | Date | Country | |
|---|---|---|---|
| 60456835 | Mar 2003 | US | |
| 60486148 | Jul 2003 | US | |
| 60509570 | Oct 2003 | US | |
| 60534871 | Jan 2004 | US | |
| 60548250 | Feb 2004 | US | |
| 60551671 | Mar 2004 | US | |
| 60551551 | Mar 2004 | US |
