Patent Application
20150209343
The present invention relates generally to topical dermal compositions for treating (both therapeutically treating and cosmetically treating) a number of different dermatological (that is skin related) diseases and conditions (such as for example acne). In particular the present invention relates to topically administered dermal compositions which comprise a retinoid encapsulated (or synonymously encompassed or enclosed or entrapped) by a lipid (such as a lipid which is a sold at a room temperature of from about 20° C. to about 25° C. and at about one atmospheric pressure, that is at sea level). The solid lipid (encapsulating a retinoid) can be in the form of “nanoparticles” which have a diameter of from about one tenth of a micron to about ten microns. More particularly the present invention relates to topical dermal compositions comprising a retinoid encapsulated by solid lipid nanoparticles that are mixed into or dispersed within a gel, the gel serving as a vehicle for the retinoid encapsulating solid lipid nanoparticles.
Human skin is composed of three primary layers, the stratum corneum, the epidermis, and the dermis. The outer layer is the stratum corneum. Its primary function is to serve as a barrier to the external environment. Lipids are secreted to the surface of the stratum corneum, where they decrease the stratum corneum's water permeability. Sebum typically constitutes 95% of these lipids. See e.g., Sebum, Cosmetics, and Skin Care by Abramovits W., et al., in Dermatologic Clinics, volume 18, issue 4, pages 617-620 (2000). In addition to maintaining the epidermal permeability barrier, sebum transports anti-oxidants to the surface of the skin and protects against microbial colonization
Sebum is produced in the sebaceous glands. These glands are present over most of the surface of the body. The highest concentration of these glands occurs on the scalp, the forehead, and the face. Despite the important physiological role that sebum plays, many individuals experience excess sebum production, especially in the facial area. An increased rate of sebum excretion is termed seborrhea.
Seborrhoeic dermatitis is also associated with seborrhea. The condition is characterized by the appearance of red, flaking, greasy areas of skin, most commonly on the scalp, nasolabial folds, ears, eyebrows and chest. In the clinical literature seborrhoeic dermatitis may be also referred to as “sebopsoriasis,” “seborrhoeic eczema,” “dandruff,” and “pityriasis capitis.” Yeast infections are a causative factor in seborrhoeic dermatitis. The yeast thrives on sebum and leaves high concentrations of unsaturated fatty acids on the skin, thereby irritating it.
Acne vulgaris is associated with clinical seborrhea and there is a direct relationship between the sebum excretion rate and the severity of acne vulgaris. Although sebum production increases during adolescence (particularly in boys, because of androgen stimulation), increased sebum alone does not cause acne. Bacteria, most importantly P. acnes, feed on sebum and as a result are present in increased numbers in persons who have acne. Much of the inflammation associated with acne arises from the action of enzymes produced by the bacteria.
Acne vulgaris is characterized by areas of skin with seborrhea (scaly red skin), comedones (blackheads and whiteheads), papules (pinheads), pustules (pimples), nodules (large papules), and in more severe cases, scarring. It mostly affects skin with the densest population of sebaceous follicles, such as the face, upper chest, and back.
There are four key pathogenic factors of acne:
Acne is still a very underserved market with treatment options that are only marginally effective. Only one product, oral Accutane® (isotretinoin) that reduces sebum production has been highly effective, but at the expense of a black box warning with significant side effects including teratogenicity that require extensive patient monitoring. Accutane® is indicated only for acne which is severe and recalcitrant to other treatment
Topical therapy is often preferred over oral therapy because of the reduced risk for adverse systemic effects. The most common topical drugs for acne can be divided into the following categories:
While many topical therapies are available, none of them address all four factors and most specialize in a few of these factors. Currently, no topical therapies in the market address excessive sebum production. Sebum is produced by the sebaceous gland, which is an appendage of the hair follicle, so it makes sense to target the sebaceous gland for more effective therapy. Since P. acnes depends on sebum to live, reduction of sebum is also thought to indirectly reduce P. acnes.
Topical retinoids primarily act by normalizing infundibular hyperkeratinization and reducing inflammation, hence topical retinoids remain a mainstay for treatment of mild-to-moderate acne. The current topical retinoid formulations do not inhibit sebum production and their use is often limited by local tolerability (i.e., skin irritation).
The following publications may be relevant to the present invention: Solid lipid nanoparticles (SLN) for controlled drug delivery, a review of the state of the art, by Muller, R., et al., European Journal of Pharmaceutics and Biopharmaceutics 50 (2000) 161-177; Lipid nanoparticles for improved topical application of drugs for skin diseases by Schäfer-Korting, M., et al., in Advanced Drug Delivery Reviews 59 (2007) 427-443; Castro, G., et al., Formation of ion pairing as an alternative to improve encapsulation and stability and to reduce skin irritation of retinoic acid loaded in solid lipid nanoparticles, International Journal of Pharmaceutics 381 (2009) 77-83; Castro G., et al., Comedolytic effect and reduced skin irritation of a new formulation of all-trans retinoic acid-loaded solid lipid nanoparticles for topical treatment of acne, Arch Dermatol Res (2011); 303:513-520; U.S. Pat. No. 5,851,538; international patent application publication WO 2004/082666; Canadian patent 2 519 697; US published patent application US 2006/0257334, and; US published patent application US 2012/0328670.
Additionally, the company SkinMedica (Carlsbad, Calif.) sells a topically applied product called “Retinol Complex” for enhancing skin tone which comprises lipid particles encapsulating retinol, as well as water, cetyl ethylhexanoate, glycine soja oil, niacinamide, polyacrylate-13, caprylic/capric triglyceride, squalane, palmitoyl tripeptide-8, dunaliella salina extract, magnolia grandiflora bark extract, tocopherol, tocotrienols, ceramide 3, bisabolol, phytosterols, squalene, tocopheryl acetate, oryza sativa bran cera, glycerin, polysorbate 20, butylene glycol, cetyl palmitate, laureth-23, trideceth-6 phosphate, sodium hydroxide, dicaprylyl ether, lauryl alcohol, polyisobutene, dextran, potassium sorbate, disodium EDTA, phenoxyethanol, and ethylhexylglycerin.
Thus, there is a need in the art, therefore, for topical compositions capable of reducing sebum production and treating the conditions associated with it.
The present invention satisfies this need by providing topical dermal compositions which can comprise microspheres, microparticles and/or nanoparticles (including nanoparticles made of a lipid or lipids) which encompass an active ingredient (such as a retinoid). The retinoid encompassing microspheres, microparticles and/or nanoparticles are mixed with, dispersed within, suspended by, emulsified with or by, etc, a carrier or vehicle, which carrier or vehicle can be gel, lotion, cream or the like. A preferred embodiment of the present invention comprises solid lipid nanoparticles encapsulating a retinoid and present within in a semi-solid (i.e. gel) vehicle.
The active ingredient can be a retinoid (such as tazarotene or isotretinoin), a prostaglandin or a prostamide. The retinoid is preferably tazarotene or a salt, ester, or amide thereof. The dermally applied compositions of the present invention are useful for treating a variety of dermatological conditions, for example dermatological conditions associated with excess sebum production, such as for example acne.
By employing a dermal composition of the present invention a retinoid (such as tazarotene) can be targeted for and delivered deep into the skin of a patient into the hair follicles of the patient where the retinoid reaches the sebaceous glands and significantly inhibit production of sebum by the sebaceous glands, thereby providing an effective treatment of a dermatological condition such as acne. The present dermal compositions can provide sustained or extended delivery of the retinoid from the encapsulating lipoid nanoparticle over a period of time from as little as a few seconds (i.e. over about 5 second after dermal application of the dermal composition to over about 100 seconds), to a few minutes (i.e. over about 1 minute after dermal administration to about 15 minutes), to a few days (i.e. from about 1 day after dermal administration to about 3 days), to several weeks (i.e. from about 1 week after dermal administration to about 3 weeks), wherein the retinoid is released from the lipid nanoparticles under either first order or under zero order release rate kinetics.
Importantly, the compositions of the invention result in fewer and reduced side effects to the surface of the skin in comparison to other known retinoid creams, gels or other formulations, which other inferior formulations do not provide a sustained or extended release formulation for the topical treatment of acne.
One embodiment of the present invention comprises a topical dermal composition which includes a plurality of nanoparticles, wherein the nanoparticles comprise a biodegradable lipid, and a retinoid or a pharmaceutically acceptable salt, ester, or amide thereof, a population of the nanoparticles have an average diameter between about 0.1 μm and about 10 μm.
The present invention also includes methods for treating a condition associated with excess sebum production. Such methods can be performed, for example, by topically applying to the skin of a patient in need thereof a composition within the scope of the present invention.
Thus, the present invention encompasses a composition for topical dermal administration comprising a retinoid encompassed by lipid particles in a gel vehicle. The retinoid can be tazarotene, the lipid is preferably a solid at room temperature and the lipid has a melting point at about or greater than about 32° C. “Room temperature” means 20-25 degrees C., and preferably about 23 degrees C. The composition can have the retinoid encompassed by a plurality of biodegradable lipid nanoparticles that are solid at room temperature. The composition can comprise a surfactant and the solid lipid nanoparticles can have an average diameter no greater than about 10 microns, no greater than about 5 μm, no greater than about 3 μm or no greater than about 1 μm. In the composition the lipid can be selected from the group consisting of glyceryl dibehenate, glyceryl behenate myristyl myristate, myristyl laurate, triglycerides of C10-C22 fatty acids, propylene glycol monopalmiteostearate, cetyl palmitate, isostearyl isostearate, and propylene glycol monopalmiteostearate, and combinations thereof. The invention also encompasses a method for treating a condition associated with excess sebum production by topically applying to the skin of a patient in need thereof the composition set forth in this paragraph and the condition treated can be for example acne vulgaris, seborrhoeic dermatitis, psoriasis, or keratosis pilaris.
The invention also encompasses a composition for topical dermal administration comprising a retinoid encapsulated by or encompassed by a lipid. The retinoid can be tazarotene and preferably the lipid is solid at room temperature and the lipid has a melting point between bout 32° C. to about 37° C. The lipid is formed into a plurality of biodegradable, solid lipid nanoparticles encompassing or encapsulating the tazarotene, which formulation (tazarotene encapsulated by solid lipid nanoparticles) can be abbreviated as “TazSLN”. Importantly, the TazSLN is mixed with or dispersed within (preferably) a gel as a carrier or as a vehicle for the TazSLN, thereby providing a dermal composition which can be abbreviated as “TazSLG” (note that TazSLN in a gel vehicle forms the TazSLG). The vehicle or carrier does not comprise a lipid. Preferably the lipid which comprises the solid lipid nanoparticles is selected from the group consisting of glyceryl dibehenate, glyceryl behenate myristyl myristate, myristyl laurate, triglycerides of C10-C22 fatty acids, propylene glycol monopalmiteostearate, cetyl palmitate, isostearyl isostearate, and propylene glycol monopalmiteostearate, and combinations thereof. Significantly, TazSLG dermal compositions described herein are stable for at least six months when stored at room temperature. Such stability being demonstrated infra by both little or no separation (i.e. no precipitation out) of the TazSLN out of the TazSLG dermal composition, and as well by continued excellent follicular delivery of the tazarotene from the six month or longer room temperature stored and then dermally applied TazSLG, with reduced skin irritation (as compared to the amount of skin irritation which results from dermal application of a same strength composition which comprises the same concentration of tazarotene in a similar vehicle, such as a gel vehicle, such as Tazaroc Gel—i.e. a control formulation), and as well as by an efficacy in the reduction of sebum and acne treatment which is greater than that obtained by the control formulation.
The invention also encompasses a composition for topical dermal administration comprising: (a) tazarotene; (b) a plurality of biodegradable, solid lipid nanoparticles encompassing or encapsulating the tazarotene, thereby forming TazSLN; and (c) a gel acting as a carrier or as a vehicle for the TazSLN, thereby forming TazSLG. The lipid can be selected from the group consisting of glyceryl dibehenate, glyceryl behenate myristyl myristate, myristyl laurate, triglycerides of C10-C18 fatty acids, propylene glycol monopalmiteostearate, cetyl palmitate, isostearyl isostearate, and propylene glycol monopalmiteostearate, and combinations thereof.
Additionally, the invention encompasses a method for treating a condition associated with excess sebum production, the method comprising the step of topically applying to the skin of a patient in need of such treatment a dermal composition comprising:
Additionally, the invention encompasses a method for treating a condition associated with excess sebum production, the method comprising the step of topically applying to the skin of a patient in need of such treatment a dermal composition comprising:
The present invention includes a composition for topical dermal administration comprising tazarotene encapsulated by a lipid, and a gel vehicle into which the lipid encapsulated retinoid is mixed or dispersed. Preferably, the lipid is a solid at room temperature and more preferably the lipid has a melting point at about or greater than about 32° C. In the invention the lipid is in the form of a plurality of biodegradable, solid lipid nanoparticles encompassing or encapsulating the tazarotene, thereby providing TazSLN, and in turn TazSLN in the gel vehicle provides TazSLG. The composition can further comprising a surfactant and the gel is preferably a polymeric formed by use of a gelling agent. Preferably, the solid lipid nanoparticles have an average diameter (i.e. size as determined for example by light scattering) no greater than about 5 μm, such as an average diameter no greater than about 3 μm and an average diameter no greater than about 1 μm.
The lipid used in the invention is preferably selected from the group consisting of glyceryl dibehenate, glyceryl behenate myristyl myristate, myristyl laurate, triglycerides of C10-C22 fatty acids, propylene glycol monopalmiteostearate, cetyl palmitate, isostearyl isostearate, and propylene glycol monopalmiteostearate, and combinations thereof, more preferred lipids are myristyl myristate, glyceryl dibehenate or glyceryl dibehenate.
The invention includes a method for treating a condition associated with excess sebum production by applying to the skin of a patient in need thereof the dermal compositions set forth above and the condition treated can be for example acne vulgaris, seborrhoeic dermatitis, psoriasis, and keratosis pilaris.
A preferred composition within the scope of the invention can comprise tazarotene encapsulated by a plurality of biodegradable, solid lipid nanoparticles, thereby forming TazSLN, and a polymeric gel vehicle into which the TazSLN is mixed or dispersed, thereby forming TazSLG, wherein the lipid comprising solid the lipid nanoparticles is selected from the group consisting of glyceryl dibehenate, glyceryl behenate, myristyl myristate, myristyl laurate, triglycerides of C10-C22 fatty acids, propylene glycol monopalmiteostearate, cetyl palmitate, isostearyl isostearate, and propylene glycol monopalmiteostearate, and combinations thereof, and wherein the polymeric gel is comprises a gel or a gelling agent selected from the group consisting of a carbomer, acacia, alginic acid, bentonite, carboxymethylcellulose, ethylcellulose, gelatin, hydroxyethylcellulose, hydroxypropyl cellulose, magnesium aluminum silicate, methylcellulose, poloxamers, polyvinyl alcohol, sodium alginate, tragacanth, and xanthan gum.
Additionally, a further method within the scope of the invention is a method for treating a condition associated with sebum production, the method comprising the step of topically applying to the skin of a patient in need of such treatment a dermal composition comprising:
Another method within the scope of the invention is a method for treating a condition associated with excess sebum production, the method comprising the step of topically applying to the skin of a patient in need of such treatment a dermal composition comprising:
The invention also includes a process for making TazSLG, as by the following steps of:
The solid lipid particles encapsulating tazarotene and in a gel vehicle (TazSLG) made by the process above are also part of the invention.
Furthermore the invention also encompasses a composition for topical dermal administration comprising a retinoid encapsulated by a fatty acid ester, and a gel vehicle into which the fatty acid ester encapsulated retinoid is mixed or dispersed.
An exemplary composition for topical dermal administration within the scope of the invention can comprise:
(a) a population of solid lipid nanoparticles comprising:
The invention is based on the discovery of stable compositions which when topically applied to the dermis (especially to the face) can be used to effectively treat certain dermal diseases and conditions, such as acne, with reduced side effects.
Unless specific definitions are provided, the nomenclatures utilized in connection with, and the laboratory procedures and techniques of analytical chemistry, synthetic organic and inorganic chemistry described herein are those known in the art. Standard chemical symbols are used interchangeably with the full names represented by such symbols. Thus, for example, the terms “hydrogen” and “H” are understood to have identical meaning. Standard techniques may be used for chemical syntheses, chemical analyses, and formulation.
The invention provides topical dermal compositions including a plurality of nanoparticles, wherein the particles include a biodegradable lipid, and a retinoid, or a pharmaceutically acceptable salt, ester, or amide thereof; wherein the particles have an average diameter between about 0.1 μm and about 10 μm.
In some embodiments, the particles have an average diameter no greater than about 5 μm. In some embodiments, the particles have an average diameter no greater than about 4 μm. In some embodiments, the particles have an average diameter no greater than about 1 μm.
Unless stated otherwise in this application, esters are derived from the saturated aliphatic alcohols or acids of ten or fewer carbon atoms or the cyclic or saturated aliphatic cyclic alcohols and acids of 5 to 10 carbon atoms. Examples include aliphatic esters derived from lower alkyl acids and alcohols, and phenyl or lower alkyl phenyl esters.
The term “amide” has the meaning classically accorded that term in organic chemistry. In this instance it includes the unsubstituted amides and all aliphatic and aromatic mono- and di-substituted amides. Examples include the mono- and di-substituted amides derived from the saturated aliphatic radicals of ten or fewer carbon atoms or the cyclic or saturated aliphatic-cyclic radicals of 5 to 10 carbon atoms. In one embodiment, the amides are derived from substituted and unsubstituted lower alkyl amines. In another embodiment, the amides are mono- and disubstituted amides derived from the substituted and unsubstituted phenyl or lower alkylphenyl amines. One may also use unsubstituted amides.
“Acetals” and “ketals” include the radicals of the formula-CK where K is (—OR)2. Here, R is lower alkyl. Also, K may be —OR7O— where R7 is lower alkyl of 2-5 carbon atoms, straight chain or branched.
The term “alkyl,” by itself or as part of another substituent, means, unless otherwise stated, a straight (i.e. unbranched) or branched carbon chain, or combination thereof, which may be fully saturated (referred to herein as a “saturated alkyl”), mono- or polyunsaturated and can include di- and multivalent radicals, having the number of carbon atoms designated (e.g. “C1-C10” means one to ten carbons). Typical alkyl groups include, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, hexyl and the like. The term “lower alkyl” refers to a C1-C6 alkyl group (e.g. methy, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, and others identifiable to a skilled person). An “alkoxy” is an alkyl attached to the remainder of the molecule via an oxygen linker (—O—).
The term “aryl” means, unless otherwise stated, an aromatic substituent of 3 to 14 atoms (e.g. 6 to 10) which can be a single ring or multiple rings (e.g., from 1 to 3 rings) which may be fused together (i.e. a fused ring aryl) or linked covalently. A fused ring aryl refers to multiple rings fused together wherein at least one of the fused rings is an aryl ring (e.g., phenyl, 1-naphthyl, 2-naphthyl, or 4-biphenyl). The term “heteroaryl” refers to aryl groups (or rings) that contain one or more (e.g., 4) heteroatoms selected from N, O, and S, wherein the nitrogen and sulfur atoms are optionally oxidized, and the nitrogen atom(s) are optionally quaternized, the remaining ring atoms being carbon. The heteroaryl may be a monovalent monocyclic, bicyclic, or tricyclic (e.g., monocyclic or bicyclic) aromatic radical of 5 to 14 (e.g., 5 to 10) ring atoms where one or more, (e.g., one, two, or three or four) ring atoms are heteroatom selected from N, O, or S.
The terms “cycloalkyl” and “heterocycloalkyl,” by themselves or in combination with other terms, represent, unless otherwise stated, non-aromatic cyclic versions of “alkyl” and “heteroalkyl”, respectively (e.g., having 4 to 8 ring atoms). Additionally, for heterocycloalkyl, a heteroatom can occupy the position at which the heterocycle is attached to the remainder of the molecule. Pharmaceutically acceptable salts of a retinoid are also contemplated for use in the practice of the invention. A pharmaceutically acceptable salt is any salt which retains the activity of the parent compound and does not impart any deleterious or untoward effect on the subject to which it is administered and in the context in which it is administered.
Pharmaceutically acceptable acid addition salts of a retinoid are those formed from acids which form non-toxic addition salts containing pharmaceutically acceptable anions, such as the hydrochloride, hydrobromide, hydroiodide, sulfate, or bisulfate, phosphate or acid phosphate, acetate, maleate, fumarate, oxalate, lactate, tartrate, citrate, gluconate, saccharate and p-toluene sulphonate salts.
Pharmaceutically acceptable salts can be derived from organic or inorganic bases. The salt may be a mono or polyvalent ion. Of particular interest are the inorganic ions, sodium, potassium, calcium, and magnesium. Organic salts may be made with amines, particularly ammonium salts such as mono-, di- and trialkyl amines or ethanol amines. Salts may also be formed with caffeine, tromethamine and similar molecules. Where there is a nitrogen sufficiently basic as to be capable of forming acid addition salts, such may be formed with any inorganic or organic acids or alkylating agent such as methyl iodide. Preferred salts are those formed with inorganic acids such as hydrochloric acid, sulfuric acid or phosphoric acid. Any of a number of simple organic acids such as mono-, di- or tri-acid may also be used.
The nanoparticles included in the compositions of the invention have an average diameter no less than about 0.1 μm and no greater than about 10 μm
As used here, the term “about,” when used in connection with a value, means that the value may not differ by more than 10%. Hence, “about 10 μm” includes all values within the range of 9 μm to 11 μm.
In one embodiment, the nanoparticles of the invention have a maximum average diameter of about 10 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 9 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 8 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 7 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 6 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 5 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 4 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 3 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 2 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 1 μm.
In another embodiment, the nanoparticles of the invention have a maximum average diameter less than about 1 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.9 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.8 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.7 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.6 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.5 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.4 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.3 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.2 μm. In another embodiment, the nanoparticles of the invention have a maximum average diameter of about 0.1 μm.
In one embodiment, the nanoparticle is shaped like a cylindrical rod. The inventors refer to such particles as “microcylinders,” even though they may have an average diameter in the nanometer range (that is, about 100 nm to about 999 nm). The microcylinders of the invention have a maximum average diameter and maximum average length such that no one such dimension is greater than about 10 μm. In other embodiments, the particles of the invention are of different geometry, such as fibers or circular discs; any geometry falls within the scope of the invention, as long as the average of any single dimension of the particle exceeds about 10 μm.
In one embodiment, the microcylinders of the invention have a maximum average diameter of about 10 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 9 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 8 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 7 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 6 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 5 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 4 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 3 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 2 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 1 μm.
In another embodiment, the microcylinders of the invention have a maximum average diameter less than about 1 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.9 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.8 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.7 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.6 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.5 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.4 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.3 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.2 μm. In another embodiment, the microcylinders of the invention have a maximum average diameter of about 0.1 μm.
In one embodiment, the microcylinders have a maximum average length of about 10 μm, about 9 μm, about 8 μm, about 7 μm, about 6 μm, about 5 μm, about 4 μm, about 3 μm, about 2 μm, about 1 μm, about 0.9 μm, about 0.8 μm, about 0.7 μm, about 0.6 μm, about 0.5 μm, about 0.4 μm, about 0.3 μm, or about 0.2 μm.
The size and geometry of the nanoparticles can also be used to control the rate of release, period of treatment, and drug (i.e. a retinoid) concentration. Larger particles will deliver a proportionately larger dose, but, depending on the surface to mass ratio, may have a slower release rate.
The retinoid of the invention can be in a particulate or powder form. In one embodiment, the retinoid itself consists of particles having the dimensions described above.
In another embodiment, a retinoid (such as tazarotene) is combined with a biodegradable lipid. In one embodiment, the retinoid is from about 1% to about 90% by weight of the composition. In another embodiment, the retinoid is from about 5% to about 85% by weight of the composition. In another embodiment, the retinoid is from about 10% to about 80% by weight of the composition. In another embodiment the retinoid is from about 15% to about 75% by weight of the composition. In one embodiment the retinoid comprises about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, or about 90% of the composition.
Suitable materials (i.e. as the lipid constituent of the nanoparticles and as the gel constituent for the vehicle for the lipid nanoparticles) for use in the dermally applied compositions of the present invention include those materials which are biocompatible with the skin so as to cause no substantial irritation or other side effects. In one embodiment, such materials are at least partially biodegradable. In another embodiment, such materials are completely biodegradable.
Examples of useful materials include, without limitation, lipids such as Crodamol MM, Crodamol SS, myristyl myristate, myrisistyl laurate (Ceraphyl 424), triglycerides of C10-C18 and of C10-C22 fatty acids (for example Gelucire 43/01), and propylene glycol monopalmiteostearate (Monosteol). Other useful lipids include lipids derived from and/or including organic esters and organic ethers, which when degraded result in physiologically acceptable degradation products. Also, as a component of the gel vehicle, polymeric materials derived from and/or including, anhydrides, amides, orthoesters and the like, by themselves or in combination with other monomers, can be used. The polymeric materials may be addition or condensation polymers, advantageously condensation polymers. The polymers can be cross-linked or non-cross-linked, for example not more than lightly cross-linked, such as less than about 5%, or less than about 1% of the polymeric material being cross-linked. For the most part, besides carbon and hydrogen, the polymers will include at least one of oxygen and nitrogen, advantageously oxygen. The oxygen may be present as oxy, e.g. hydroxy or ether, carbonyl, e.g. non-oxo-carbonyl, such as carboxylic acid ester, and the like. The nitrogen may be present as amide, cyano and amino. The polymers set forth in Heller, CRC Critical Reviews in Therapeutic Drug Carrier Systems, Vol. 1, CRC Press, Boca Raton, Fla. 1987, pp 39-90 (Biodegradable Polymers in Controlled Drug Delivery), the contents of which are incorporated herein by reference, which describes encapsulation for controlled drug delivery, may find use in the present compositions.
Other additional polymers (as a component of the vehicle or carrier) include, for example, polymers of hydroxyaliphatic carboxylic acids, either homopolymers or copolymers, and polysaccharides, lipid nanoparticle, and mesoporous silica nanoparticle. Polyesters of interest include polymers of D-lactic acid, L-lactic acid, racemic lactic acid, glycolic acid, polycaprolactone, and combinations thereof. Generally, by employing the L-lactate or D-lactate, a slowly eroding polymer or polymeric material is achieved, while erosion is substantially enhanced with the lactate racemate.
Among the useful polysaccharides are, without limitation, calcium alginate, and functionalized celluloses, particularly carboxymethylcellulose esters characterized by being water insoluble, a molecular weight of about 5 kD to 500 kD, for example.
Other polymers of interest include, without limitation, polyesters, polyethers and combinations thereof which are biocompatible and may be biodegradable and/or bioerodible.
Some preferred characteristics of the polymers or materials for use in the present invention may include biocompatibility, compatibility with the therapeutic compound, ease of use of the polymer in making the compositions of the present invention, a half-life in the physiological environment of at least about 6 hours, preferably greater than about one day, and water insolubility.
The biodegradable lipids which form the nanoparticles are desirably subject to enzymatic or hydrolytic instability. The biodegradable lipid of the composition of the invention may comprise a mixture of two or more biodegradable lipids. For example, the composition may comprise a mixture of a first biodegradable lipid and a different second biodegradable lipid. One or more of the biodegradable lipids may have terminal acid groups.
Release of a drug (i.e. tazarotene) from an erodible lipid is the consequence of several mechanisms or combinations of mechanisms. Some of these mechanisms include desorption from the systems surface, dissolution, diffusion through porous channels of the hydrated polymer and erosion. Erosion can be bulk or surface or a combination of both.
One example of a composition of the invention includes tazarotene within a biodegradable lipid nanoparticle matrix. The composition system may have an amount of tazarotene from about 0.005 wt percent to about 1% or about 5% by weight of the system.
The release of tazarotene from the composition may include an initial burst of release followed by a gradual increase in the amount of tazarotene released, or the release may include an initial delay in release of tazarotene followed by an increase in release. When the biodegradable lipids substantially completely degraded, the percent of tazarotene that has been released is about one hundred percent.
It can be desirable to provide a relatively constant rate of release of tazarotene from the particles. However, the release rate may change to either increase or decrease depending on the formulation of the encapsulating nanoparticle. In addition, the release profile of tazarotene may include one or more linear portions and/or one or more non-linear portions. In one embodiment, the release rate is greater than zero once the system has begun to degrade or erode.
The lipid nanoparticles of the invention can be monolithic, that is, having the active agent or agents (i.e. a retinoid) homogenously distributed through the lipid matrix or encapsulated, where a reservoir of active agent is encapsulated by the lipid. The nanoparticle can be either monolithic with regard to retinoid distribution within the lipid or the retinoid can be encapsulated by the lipid. Greater drug release rate control can be afforded by the encapsulated, reservoir-type nanoparticles. Thus, nanoparticles can be prepared where the center may be of one material and the surface may have one or more layers of the same or a different material, where the layers may be cross-linked, or of a different molecular weight, different density or porosity, or the like.
The proportions of tazarotene and lipid in a nanoparticle can be empirically determined by formulating several drug delivery systems with varying proportions. A USP approved method for dissolution or release test can be used to measure the rate of release (USP 23; NF 18 (1995) pp. 1790-1798). For example, using the infinite sink method, a weighed sample of the nanoparticles is added to a measured volume of a solution containing 0.9% NaCl in water, where the solution volume will be such that the drug concentration is after release is less than 5% of saturation. The mixture is maintained at a temperature below the melting point of the lipid 37° C. and stirred slowly to maintain the nanoparticles in suspension. The appearance of the dissolved drug as a function of time may be followed by various methods known in the art, such as, for example, spectrophotometrically, HPLC, mass spectroscopy, and others identifiable to a skilled person, until the absorbance becomes constant or until greater than 90% of the drug has been released.
In addition to tazarotene and lipid, the nanoparticles and/or the vehicle disclosed herein can include effective amounts of buffering agents, preservatives and the like. Suitable water soluble buffering agents include, without limitation, alkali and alkaline earth carbonates, phosphates, bicarbonates, citrates, borates, acetates, succinates and the like, such as sodium phosphate, citrate, borate, acetate, bicarbonate, carbonate and the like. These agents advantageously present in amounts sufficient to maintain a pH of the system of between about 2 to about 9 and more, for example at about pH 4 to about 8. As such the buffering agent may be as much as about 5% by weight of the total drug delivery system. Suitable water soluble preservatives include sodium bisulfite, sodium bisulfate, sodium thiosulfate, ascorbate, benzalkonium chloride, chlorobutanol, thimerosal, phenylmercuric acetate, phenylmercuric borate, phenylmercuric nitrate, parabens, methylparaben, polyvinyl alcohol, benzyl alcohol, phenylethanol and the like and mixtures thereof. These agents can be present in amounts of from about 0.001% to about 5% by weight; in another embodiment, they can be present in amounts from about 0.01% to about 2% by weight.
In addition, the nanoparticles and or the vehicle can include a solubility enhancing compound provided in an amount effective to enhance the solubility of tazarotene relative to substantially identical systems without the solubility enhancing compound. For example, an implant can include a β-cyclodextrin, which is effective in enhancing the solubility of tazarotene. The β-cyclodextrin can be provided in an amount from about 0.5% (w/w) to about 25% (w/w) of the particle. In other embodiments, the β-cyclodextrin is provided in an amount from about 5% (w/w) to about 15% (w/w) of the particle.
Additionally, release modulators such as those described in U.S. Pat. No. 5,869,079, the contents of which are incorporated herein by reference, may be included in the nanoparticles. The amount of release modulator employed will be dependent on the desired release profile, the activity of the modulator, and on the release profile of the retinoid in the absence of modulator. Electrolytes such as sodium chloride and potassium chloride may also be included in the nanoparticles or in the vehicle. Where the buffering agent or enhancer is hydrophilic, it may also act as a release accelerator. Hydrophilic additives act to increase the release rates through faster dissolution of the material surrounding the drug particles, which increases the surface area of the drug exposed, thereby increasing the rate of drug bioerosion. Similarly, a hydrophobic buffering agent or enhancer dissolve more slowly, slowing the exposure of drug particles, and thereby slowing the rate of drug bioerosion.
Various techniques can be employed to produce the nanoparticles described herein. In one embodiment, particles are produced using a solvent evaporation process. Such a process can include steps of liquid sieving, freeze drying, and sterilizing the various composition compounds. In one embodiment, a retinoid and a lipid are combined with methylene chloride to form a first composition, and water and polyvinyl alcohol are combined to form a second composition. The first and second compositions are combined to form an emulsion. The emulsion is rinsed and/or centrifuged, and the resulting product dried. In a further embodiment, the emulsion undergoes an evaporation process to remove methylene chloride from the emulsion. For example, the emulsion can be evaporated for about 2 days or more. In this embodiment, the method includes sieving retinoid-containing nanoparticles in a liquid phase, as compared to a method which includes sieving retinoid-containing nanoparticles in a dry phase. This method can also comprise a step of freeze drying the sieved nanoparticles, and a step of packaging the freeze dried nanoparticles.
In one embodiment, the compositions of the invention can be used to treat conditions associated with excess sebum production. Such conditions include, for example, acne vulgaris, seborrhoeic dermatitis, and keratosis pilaris, as well as others identifiable to a skilled person. In another embodiment, the compositions of the invention can be used to treat those conditions in which it would be beneficial to suppress the function of the sebaceous gland. Such conditions include, for example, sebaceous cyst, sebaceous hyperplasia, sebaceous adenoma, and sebaceous gland carcinoma.
The following examples illustrate embodiments of the invention and are not intended to limit the scope of the invention. Where units, amounts or concentrations are not set forth in the Tables infra the components or constituent in the Tables are shown as weight percent (wt. %).
In this Example 1 set of experiments a number of tazarotene containing (as encompassed by or encapsulated by) SLN (SLN meaning solid lipid nanoparticle or solid lipid nanoparticles) were made and tested. It is known to topically apply tazarotene simply mixed into a gel or into a cream base or vehicle to treat acne and psoriasis, but so applying it to the skin can result in significant dermal irritation. It has been discovered by the Applicant that targeted delivery of a retinoid such as tazarotene, by preparing the tazarotene encompassed within biodegradable, solid at room temperature (20 to 25 degrees C., and in particular about 23 degrees C.) lipid nanoparticles, to the dermal sebaceous glands can enhance the efficacy of the treatment of a dermal condition such as acne by reducing sebum production by the glands and can also provide the added benefit of reducing irritation by decreasing exposure of the tazarotene per unit of time to the epidermis when the tazarotene is so topically applied to the skin formulated within SLN. Thus it has been determined that encapsulation of tazarotene in solid lipid nanoparticles can reduce exposure of tazarotene directly on the skin surface thus reducing the potential for skin irritation. Additionally, it has been discovered by the Applicant that the SLN-encapsulated tazarotene can improve the efficacy via the encapsulated system by preferentially depositing into the hair follicle. Once the encapsulated system is deposited into the hair follicle, the tazarotene is be released directly into the sebum producing sebaceous glands.
An important aspect of the invention is the creation of solid lipid nanoparticles (“SLN” or “particle” or “lipid particle”) for the delivery of tazarotene or other retinoid or other active pharmaceutical ingredient (e.g. an API such as bimatoprost) that can benefit from improved tolerability and efficacy by delivery into the hair follicle. Thus the Applicant determined how to make SLNs and used a hamster flank organ model to show sebaceous gland activity reduction.
As part of the development of SLN formulations comprising tazarotene several different lipids with varying melting points and chemical compositions were evaluated. The preferred lipid is a lipid into which can dissolve tazarotene, that can be easily dispersed in a water and surfactant system, and that can be processed through a high pressure fluid processor to thereby obtain SLN with a generally unimodal size distribution. Table 1 outlines the formulation compositions tested in this Example 1. Note that Table 1 identifies three suitable particular surfactants (polysorbate 80, Solutol HS 15 and Soluplus).
It was determined from the results set forth in Table 1 that two desirable (desirable because use of each of these two lipids resulted in desirable SLN diameters) lipids for making the SLN are firstly: myristyl myristate (available commercially as Crodamol MM). Myristyl myristate is also referred to as: tetradecanoic acid; tetradecyl ester; tetradecyl ester tetradecanoic acid; tetradecyl myristate; tetradecyl tetradecanoate; ceraphyl 424; Cyclochem MM; myristic acid, tetradecyl ester; tetradecyl myristate, and as; tetradecyl tetradecanoate, and is the ester of myristyl alcohol and myristic acid). The other desirable lipid is cetyl palmitate (C32H64O2), which is available commercially as Crodamol SS.
Other lipids that are comparable to Crodamol MM and SS are also suitable as being expected to perform comparably can include myristyl laurate (Ceraphyl 424), triglycerides of saturated C10-C18 (or C10 to C22) fatty acids (such as Gelucire 43/01), isostearyl isostearate and propylene glycol monopalmiteostearate (Monosteol).
Table 2 summarizes the formulations and nanoparticle size information as influenced by the amount of surfactant added to the formulation. Thus nanoparticle size (measured as D90) decreased with increasing amount of surfactant added to the formulation.
Formulations from Table 1 and Table were selected 2 for an in vivo hamster flank organ model used to assess sebaceous gland reduction. The hamster study involves topical dosing of the selected formulations to the shaved flank skin with proper control on the right flank (the left flank of the same animal serves as the control). Treatment was conducted once a day for 5 days over a 4 week period. Following treatment the flank tissues were harvested, fixed, sectioned and sebaceous gland areas were measured with the treatment side being compared to control side by t-TEST. Drug treated groups were also compared with the vehicle treated group by one-way ANOVA. In more detail the protocol for the hamster flank organ model used was:
The formulations studied in the hamster model are listed in Table 3 below:
The results in
The SLN delivery system was further evaluated in the in vivo hamster flank organ model by studying the effects of accutane-loaded SLNs on sebaceous gland reduction. Accutane is also a retinoid like tazarotene that has been used (in a cream not in a SLN) for the treatment of acne and psoriasis. The formulations studied in the hamster model (based on the same protocol as previously described) are listed in Table 5 below.
The results in
The impact of Solutol HS15 concentration on the SLN-tazarotene formulation stability was also studied. The stability of the formulations were evaluated based on the particle size and lipid crystallinity, as measured by laser light scattering and differential scanning calorimetry, respectively, over a two month period (Day 1, 1 month and 2 month time points). The formulations listed in Table 6 were analyzed for both properties, whereas the formulations listed in Table 7 were only studied for the latter.
The stability of tazarotene-loaded SLN formulations were evaluated based on particle size, lipid crystallinity and visual inspection. First, increasing the concentration of Solutol HS15 corresponded with reduced SLN particle sizes. Second, the SLN formulations (Table 6) did not exhibit significant changes of particle size over a two month period (
In this Example 2 it was determined that a preferred lipid for making the tazarotene incorporating SLN is glyceryl dibehenate or glyceryl behenate (available commercially as Compritol 888 ATO) because of the good compatibility of the lipid with the tazarotene, and for the desirable lipid melting point (72° C.) which ensures the solid state of the final particles when applied to the skin and into the skin hair follicles (32-37° C.) upon such targeted topical delivery of the SLN. The Applicant has previously studied site specific delivery of bimatoprost and tazarotene to the hair follicles, including particulate systems including micro/nano solid lipid particulates, PLGA microspheres (MS), mesoporous silica particulates, liposomes, neosomes, micelles, and nanoemulsions.
In this Example 2 tazarotene-containing solid lipid particulates comprising Compritol 888 ATO and/or Crodamol MM as the solid lipids used were developed and characterized. The formulations contained 5% of the solid lipid, 0.1% of Taz, and 0.5 Solutol HS-15, prepared using a homogenizing process. The encapsulation efficiency for both lipids was 100% or near 100% as shown in Table 10. The DSC for Compritol particulate system with is shown in
As shown in
The procedures for encapsulating the tazarotene and determining potency are set forth below.
This Example 3 summaries a series of in vitro and in vivo experiments carried out which led to the Applicant's discovery and development of particular desirable formulations, including formulations comprising tazarotene encompassed by solid lipid nanoparticles and in a gel vehicle for effective treatment of dermal conditions. Thus, formulations comprising: tazarotene encapsulated within polymeric (i.e. PLGA) microspheres in a gel vehicle (“MSG”); formulations comprising tazarotene encapsulated within polymeric microspheres in a cream vehicle (“MSC”), and; formulations comprising tazarotene encapsulated or encompassed by solid lipid nanoparticles in a gel vehicle (referred to as “TazSLG” or simply as “SLG”) were made and evaluated. The weight % (% w/w) of the tazarotene in these various formulations was 0.1% or 0.04% tazarotene (“taz”). It was determined that the TazSLG formulations were the most desirable formulations. It should be understood that TazSLG comprises tazarotene encapsulated within solid lipid nanoparticles (TazSLN), and that the TazSLN are mixed in and dispersed throughout a non-lipid vehicle or carrier. Preferably the vehicle is a gel, such as a polymeric gel and/or a gel made using a polymeric gelling agent. Solid means a solid at room temperature.
Desirable TazSLG formulations can have for example 0.04 wt % and 0.1 wt % concentrations. The tazarotene containing TazSLG preferred formulations were chemically stable for more than 3 months at 25° C., and passed the preservative effectiveness test according to USP, EP-A and EP-B. They had no change in appearance. In non-clinical studies, the desirable TazSLG was the most effective formulation in reducing the size of sebaceous glands and the local irritation in the hamster model, and the most effective in improving dermal tolerance in the minipig model among MSG, MSC and other SLG (equivalently TazSLG) formulations. It is believed that the present TazSLG formulation is the first topical drug product under pharmaceutical development using tazarotene encapsulated solid lipid nanoparticulate technology. By these Example 3 experiments it was discovered two desirable formulations (with either 0.1% or 0.04% tazarotene % w/w concentration in the formulation), as shown in Table 11. The function of each component in the formulation is also described in Table 11, which shows that the preferred lipid used in the solid lipid phase was Compritol 888 ATO and that the preferred gel or gelling agent was Carbopol 974P.
A unique manufacturing process for making the TazSLG formulations was also developed, as outlined in
Detailed aspects of the manufacturing procedures outlined in
a. Preparation of TazSLN
A suspension of tazarotene encapsulating solid lipid nanoparticles (TazSLN) was made by a hot melt homogenization method using a microfluidizer M-100P (Microfluidics, MA) as follows:
1) A lipid phase comprising compritol ATO 888 (8.4%), as well as BHA (0.06%), BHT (0.06%) and the tazarotene (0.12%) was weighed and heated to 80-85° C., while a separate aqueous phase was made by mixing Solutol HS 15 (2.4%) and deoxygenated water which was then heated to the same temperature.
2) After agitation, the aqueous phase was poured into the lipid phase and mixed for about 5 minutes using a high speed magnetic stirring to form a milky mixture.
3) The mixture was then homogenized at 15,000 rpm for 5 minutes with a probe homogenizer (SilentCrusfier M, Heidolph), and then added into the microfluidizer, which was pre-warmed at 80-85° C. for 5 minutes.
4) The homogenized mixture was quenched to 5° C. temperature using a circulating water bath, thereby preparing an aqueous suspension of TazSLN, which was then collected into an amber glass bottle.
b. Preparation of Gel Phase
A 4% (by weight/weight) carbopol stock solution (containing carbopol and water only) was prepared by slowly and uniformly adding carbopol to the water phase to make a final carbopol concentration of 4.0% under slow agitation (stirring) to avoid the formation of lumps. Increase the agitation (stirring) to medium speed (at or greater than 500 rpm) afterwards to facilitate mixing. Keep agitation (stirring) for or for more than 3 hours until the formation of a uniform dispersion, thereby preparing the gel phase.
c. Preparation of TazSLG
1) The TazSLN suspension prepared (83.3%, 83.3 g for 100 g final gel), and added 0.2% methylparaben (0.2 g) and 0.1% propylparaben (0.1 g) was weighed into the TazSLN suspension and stirred using an overhead mixer (e.g. Heodoolph RZR 2051) at 300 rpm. EDTA Sodium (0.05 g, 0.05%) and sodium thiosulfate (0.1 g, 0.1%) were then added into the TazSLN suspension under stirring. Stirring was continued at room temperature for 1 hour or more until dissolved (by observing the bottom of the beaker for the added solids)
2) A 4% stock carbopol stock solution was then weighed to make the carbopol final concentration in the formulation of 0.35%. Phenoxylethanol (1.0%) was then weighed into the TazSLN suspension of step c. 1) above and stirred for about an hour until the formation of a uniform dispersion.
3) Drop by drop tromethanmine solution (500 mg/mL) was added into the mixed dispersion under stirring. The change of pH value was monitored using a recently calibrated pH meter. Then the final pH was adjusted to 5.5-6.0. Additional water was to make up to 100 g of the total weight of the formulation.
4) The mixture was stirred for another 60 minutes, thereby forming TazSLG.
5) The TazSLG was placed into a package, sealed and labeled.
In step a. 1) above Solutol HS 15 is Macrogol 15 hydroxystearate (Ph. Eur.) which in its USP monograph is known as Polyoxyl 15 hydroxystearate U. Solutol HS 15 can be used as a nonionic solubilizer as an emulsifying agent or as a surfactant and is made by reacting 15 moles of ethylene oxide with 1 cmole of 12-hydroxy stearic acid.
It was determined that a microparticle or nanoparticle system can be used for follicular targeted drug with improved efficacy and with reduced skin irritation resulting. The present invention is the first microparticle or nanoparticle system formulated for and effective for follicular drug (i.e. tazarotene) delivery technology. Thus the Applicant has developed tazarotene loaded microsphere dispersions and, tazarotene loaded solid lipid nanoparticles (SLN) in a gel (TazSLG) for reducing both size and activity of mammalian sebaceous glands, as demonstrated for example in a hamster flank organ model, was also developed. It was discovered that the effect of these particulate systems were superior to the effects of the commercially available TAZORAC gel, which does not contain any microparticles or nanoparticles, but only tazarotene dispersed in a gel.
Considering the complexity of microparticle and nanoparticulate systems and the potential interaction of microsphere systems with topical vehicles, gel dispersions were also studied. Thus, five micro/nano particulate formulations containing 0.1% tazarotene were made and evaluated, these five being the MSG1, MSG2, MSC, SLG1 and SLG2 formulations shown in Table 12. Using the commercially available 0.1% Tazorac® Gel formulation as the control (that is as compared to the results obtained in the same model system using the 0.1% Tazorac® Gel) the MSG1 and MSG2 formulations showed substantial reduction of skin irritation and some improvement in efficacy. MSC showed good efficacy but little improvement in skin irritation. Formulation SLG2 (equivalently TazSLG2) showed the best overall performance. To improve the stability of the SLG2 formulation to the SLG2 formulation there was added of 0.05% of butylated hydroxyanisole (BHA) and 0.05% of butylated hydroxytoluene (BHT), as shown in Table 11 (BHT is incorrectly spelled as butylated hydroxytoluent in Table 11). Deoxygenated water, yellow light and nitrogen protection were also applied in manufacture process to reduce the degradation of the tazarotene during the manufacturing process. This formulation (i.e. the Table 12 SLG2 formulation improved as noted in Table 11) is the desirable formulation SLG2-2. As a result of the reformulation and process changes for SLG2-2, chemical stability was considerably improved, and the impurity content was less than 0.9%. In addition, 1.0% phenoxyethanol was also incorporated in SLG2-2 to improve antimicrobial activity. As a result of formulation modification and process improvement, SLG2-2 passed 3 month stability and antimicrobial preservative effectiveness test (APET) against EP-A study. Thus two desirable formulations of the present invention of a retinoid (e.g. tazarotene) in solid lipid nanoparticles in a gel vehicle are shown in Table 11.
Tazarotene is a member of the acetylenic class of retinoids, and is a retinoid prodrug which is converted to its active form, the cognate carboxylic acid of tazarotene, by rapid deesterification in animals, including in man. Tazarotenic acid binds to all three members of the retinoic acid receptor (RAR) family: RARα, RARβ, and RARγ but shows relative selectivity for RARβ, and RARγ and may modify gene expression. Common side effects include worsening of acne, increased sensitivity to sunlight, dry skin, itchiness, redness and in some cases extreme drying and cracking of skin. Solubility of tazarotene in Compritol ATO 888 (82° C.) was determined to be 3-4 weight, and no crystalline drug was detected by DSC or PXRD analysis (at 1% or at 4% in Compritol).
A desirable target average particle (population) size (diameter) for the tazarotene encapsulating solid lipid nanoparticles was about 1 micron to about 10 microns and in particular from about 2 microns to about 7 microns. The lipid used to make the solid lipid nanoparticles can be for example one of the Table 14 lipids.
Suitable surfactants present in the gel vehicle can be one of more of the surfactants shown in Table 15.
The TazSLG formulations were formulated as set forth supra and tested in the hamster model. The TazSLN in gel (thereby forming TazSLG) dispersions were freshly prepared using a microfluidizer for the in vivo test. The average particle size was less than about 1 μm.
As noted above, the results from the hamster model showed that TazSLG reduced sebaceous glands, and also reduced skin irritation.
A desirable TazSLN comprised as the lipid myristyl myristate (i.e. Crodamol MM) and Poloxamer. It was also determined that because the solid lipid particles in the vehicle of the formulation have a relatively high melting point (greater than 37° C.) and therefore can assist retention of the integrity of the formulation after it's topical application to the skin (which facilitates penetration by the formulation into deep follicles), therefore a high melting point lipid such as glycerol behenate (i.e. Compitrol 888 ATO) can alternately be used in the SLG. Thus, using a combination of Compitrol and Solutol HS 15, SLN2 was formulated. Both SLN1 and SLN2 were physically stable for at least 2 weeks based on appearance and microscope images. The constituents of both the SLG1 and SLG2 formulations are shown by Table 17 (in the table “API” means active pharmaceutical ingredient).
A first three month stability study using the initial TazSLG1 and tazSLG2 formulations resulted after the three months in the presence of undesirable oxidation products at levels greater than 1%. Therefore these initial formulation were modified (thus becoming the desirable TazSLG1-2 and TazSLG2-2 formulations) by addition of BHA and BHT to further prevent oxidation and by addition of phenoxyethanol to increase antimicrobial activity. Additionally the manufacture process was improved by using deoxygenated water, yellow light for reducing photo degradation and nitrogen protection to lower API degradation during manufacture. A second three month stability study of the two so modified TazSLG formulation, with the altered manufacturing process, shown significantly reduced degradation (as determined by the presence in the formulation of the amount of tazarotene oxidation product, as shown by
A scale up process for TazSLG was developed to permit increasing the amount of TazSLN made from 20 g to 1 to 2 kg batches. The particles size distribution of the dispersion and the manufacture process were shown in respectively
The type and level of the excipients in the SLG formulations was further improved. For example, Compritol was selected primarily due to its high melting point. Other solid lipids with the melting point greater than 7° C. are also suitable for use in the TazSLG formulations. As noted supra three antioxidants were included in a desirable SLG formulation. Additionally, it was determined that SLN is best manufactured at 5-10° C. above the melting point of the lipid materials used. Therefore a SLN comprising Compritol ATO 888 was made at around 75-80° C. Furthermore, it was determined that use of 9500 psi during the TazSLN manufacturing produced the best formulations in terms of particle size distribution (i.e. when made at 9500 psi the particle size distribution of the SLNs was sharply centered at 1 micron. Further, it was determined that an optimal lipid content was 8.4 wt %. Thus it was possible to make up to 1-2 kg batches of the TazSLN1 and 2 formulations using a pressure of 9500 psi, tank temperature of 82° C., and number of passes 20.
Table 18 shows particle size distribution, viscosity and pH of six so made TazSLN2 formulations: SLG2 0.1%, GLP SLG2 0.1% (SLG2-2) and 0.04% (SLG2-9).
In order to improve the stability of the TazSLG2 formulations two antioxidants BHA and BHT were added to the TazSLG formulations. Secondly, deoxygenated water and yellow light were employed to minimize the effect on API oxidization. This resulted in the SLG2-2 formulations after preparation and after one month of storage having less than 0.5% of oxidization product and total impurity. Additional anti-oxidants vitamin E (in formulation SLG2-5), vitamin C (in formulation SLG2-6) and propyl gallate (in formulation SLG2-7) were incorporated into the SLN formulations as shown in Table 19. These later 3 formulations were whitish gel after gel preparation. The “832” (an impurity resulting from oxidation of tazarotene) impurity level for SLG2-5 and SLG2-6 was only 0.2-0.3% at time zero (“T0”), and no other impurities were observed. The incorporation of propyl gallate resulted in that formulation of an 832 impurity of 0.26%, while the total impurity reached up to 0.92%. The 832 impurity level at month 2 was less than 0.9% for SLG2-5 and SLG2-6, irrespective of the storage temperature. The 832 impurity level in SLG2-7 formulation was also <0.9% at the end of 2 month at 25° C., but increased up to 1.1% at 40° C., which has exceeded the 0.9% limit. Finally, SLG2-2 was found to be the formulation with the best chemical stabilities.
To improve the dispersion of SLNs in the gel and prevent their aggregation 0.2% Tween 80 in tazSLG2-4 was used. In SLG2-8, 0.5% instead of 1.0% phenoxyethanol for antimicrobial activity were used. The 0.04% SLG2 showed improved efficacy and reduced irritation, thusly SLG2-9 was formulated as well. All the formulations, except the SLG2-2, had an oxidization level greater than 0.5% after 3 month storage. Although SLG2-2 had slightly higher oxidization level than SLG2-3 the 832 level was still below the 0.9% limit. Formulations stored at 40° C. led to higher levels of total impurities, but most of them, except SLG2-2 and SLG2-9, fell below 1.0%. SLG2-2 and SLG2-9 reached over 1.6% of total impurity, while their oxidization level reached 0.9% and 1.0%, respectively. Considering the drug strength, the absolute amount of the impurity in SLG2-9 should be 40% lower than that in SLG2-2. These data showed that the chemical stability of these formulations at 25° C. met the 3 month criteria.
The TazSLG formulations described herein both improved efficacy by reducing the sebaceous glands, and minimized the side effects like irritation by encapsulating drugs into micro/nano particles. Formulations were targeted for the hair follicles so that particles can enter the hair follies and provide a sustained release directly into the sebaceous gland. Thus the particle size and integrity of the particles are critical to the successful development of a product, and need to be assessed. The pH of all the formulations remained around 7.0 at both temperatures (25° C. and 40° C.), as measured by ASET. At 25° C., the viscosity of all the TazSLG2 related formulations increased, even reaching a 2-fold change at the end of 3 months. In contrast, tazSLG1 formulations had a decreased viscosity along with time. At 40° C., the viscosity of the SLG2 related formulations either remained plateaued (SLG2-2, SLG2-4, SLG2-8, SLG2-9) or increased only slightly (SLG2-3), while SLG1 formulations had a decreased viscosity at the end of 3 months. At 25° C., the solid form of Compritol solid lipid particles may slowly change and reach a new equilibrium, and the particles tended to form flocculates which increase the viscosity especially at low shear rate. The viscosity changed significantly in SLG2-2 but not in SLG2. The SLG1 comprising Crodamol showed decreased viscosity along with time, even at 40° C. storage conditions. The SLG1-2 formulation has a viscosity of 8 Pa·s, while SLG2-2 has a viscosity above 126 Pa·s. 10% crodamol was used in SLG1-2, while in SLG2-2, 7% compritol was used.
Excellent delivery of the tazarotene from both the TazSLN and TazSLG formulations into the hair follicles of mammals was found. For example follicular delivery of the formulations ex vivo into pig ears was studied. The SLN comprising the lipid crodamol had an average particle size of 0.4 μm, while the SLN comprising the lipid compritol had an average particle size of 1.9 μm. It was discovered that both these TazSLNs formulations effectively penetrated into numerous and essentially all the hair follicles present in the skin of the pig ears they were applied to. The smaller SLN penetrated deeper into the pig ear follicles. The TazSLG-2 penetrated the hair follicles deeper than did the SLG2-4. The only difference between SLG2-2 and SLG2-4 is that SLG2-4 comprised 0.2% Tween. Thus, the experiments as summarized by Table 20 showed that the solid lipid nanoparticles (SLN) used as either TazSLN or as the SLN from the TazSLG formulations in either case the SLNs penetrated into the porcine hair follicles.
An in vivo hamster (shaved) flank efficacy study was performed using MSG, MSC and TazSLG formulations was carried out. The formulation which comprised 0.5 wt % carbopol, 10 wt % glycerin, 15 wt % propylene glycol, and 10 wt % PEG 400, achieved the highest reduction of sebum production by follicular sebaceous gland (about a 40% reduction as compared to control). An alternate formulation which the same ingredients except for having 1.0 wt % carbopol caused about 27% sebum reduction of sebum production, as compared to control. This indicated the strong effect of viscosity, with lower viscosity being preferred to obtain a higher sebum reduction. The MSG F1 (PEG), formulation which is equivalent to the MSG1 formulation comprised 0.5% carbopol and 60% glycerin, and caused a sebum reduction of 29.2%. MSG2 contained 30% glycerin and 30% PEG 400 and 0.35% carbopol, but had a sebum reduction of only 12.4%. It is believe that the propylene glycol facilitates the penetration of MS into the hair follicles. Taz SLG1 and MSC formulations achieved better efficacy than Tazorac® Gel (˜30% reduction in sebum production versus 22%). For PLGA MS, the limited ability to achieve higher and more consistent drug release is an obstacle to better efficacy.
The effects of formulations to cause after topical application an increase in epidermal thickness and irritation scores was also examined. MSC, aged MSC, Tazorac® Gel, MSG2, F5LV formulations achieved similar epidermal thickness (about 60 μm), while MSG1 and F5HV yielded a thickness of about 50 μm. These results showed that the use of vehicle or co-solvents themselves may increase the epidermal thickness.
Additionally, five TazSLG formulations were tested in the hamster model, these being the SLG1 0.04%, SLG1 0.1%, SLG2 0.04%, SLG2 0.1% and Tazorac 0.1% commercial gel formulations. The SLG2 formulation showed very good efficacy at both the 0.04% and 0.1% tazarotene concentrations, and is a preferred formulation (causing about sebaceous inhibition of the sebum producing follicular glands). In contrast, SLG1 0.1% had an inhibition of 23.5%, while SLG1 0.04% 31.1%. Interestingly, all the SLG formulations, irrespective of the drug strength, showed similar epidermal thickness as caused by the Tazorac gel 0.04% Notably while the Tazorac gel had an average irritation score of 9.2, the SLG1 formulations showed a score less than 5 and for the lower (0.04 wt %) tazarotene concentration SLG2 there was even lower irritation. The SLG1 also worked better at the lower 0.04% concentration too.
A further experiment were conducted to study the effects of high viscosity formulations on the efficacy the formulations. The formulations used to obtain the Table 21 had viscosities between about 150 to about −200 pa·s at room temperature (about 20-23 or 20-25 degrees C.), while other formulations tested has viscosities above about 800 pa·s at room temperature. The particle size of the solid lipid nanoparticle (SLN), after preparation, was less than 10 μm. The difference between SLG2 and SLG2-2 lied in different compositions. SLG2-2 had BHA, BHT, and phenoxyethanol, while SLG2 did not have these components.
Surface irritation of SLG2 related formulations appears similar in the hamster model. The pig ear study was also performed using the SLG2-2 formulation (Table 20). 75% of all hair follicles showed SLN penetration, and the average deepest penetration can reach 445 μm. The Table 20, SLG2-4 formulation had additional 0.2% Tween 80. The use Tween 80 was added to improve the dispersion of SLNs in gels, and prevent the aggregation of lipid particles. The SLG2-4 formulation led to the delivery of SLNs into all the available hair follicles in the skin. These results showed that, despite the increased viscosity of SLG2-2, efficient hair follicle delivery and good efficacy were still achieved. Interestingly use of 0.04% API strength led to significantly improved efficacy.
An experiment with five of formulations MSG1, MSG2, MSC, SLG1, SLG2 in a one month mini pig tolerance study was carried out. The design for this study is shown by Table 22. In this study there were 5 groups of pigs, each dosed daily for 28 days with the three formulations shown for that group (the three formulations included one vehicle formulation and one known Tazaroc gel formulation).
As shown in
The TazSLG2 formulation proved to be the best formulation in the mini pig tolerance study as shown by
A number of formulations have been evaluated based on in vivo tolerability, in vivo efficacy, chemical and physical stability, antimicrobial activity, manufacturability. The TazSLG2 formulations with a strength of 0.1% and 0.04% are desirable tazarotene encapsulated into SLN as SLG formulations.
As set forth supra a preferred TazSLG dermal compositions comprise TazSLN in a gel vehicle. A gel is a semisolid to solid, jelly like material that is a substantially dilute cross linked system that exhibits essentially no flow when in the steady-state. the dermal compositions can, instead of a gel vehicle, alternately comprise a viscous liquid carrier, such as lotion, which comprises a lower molecular weight polymer as compared to a gel. By weight a gel is mostly liquid but behaves like a solid due to a three-dimensional cross-linked network within the liquid. Thus a gel is a non-fluid colloidal network or polymer network that is expanded throughout its whole volume by a fluid (such as water, in the case of a hydrogel).
As noted supra a preferred TazSLG formulation comprises a gel made from a carbopol (a carbopol is also known as a carbomer). A carbomer is a homopolymer of acrylic acid cross linked with a polyalcohol allyl ether. A desirable TazSLG formulation comprises a gel made using about 0.35 wt % to about 0.5 wt % carbopol, 0.05% EDTA (ethylenediaminetetraacetic acid, as chelating agent), 0.1% sodium thiosulfate, 0.05% BHT, 0.05% BHT, 2% solutol HS 15, 0.2% methylparaben, 0.1% propylparaben, and 1% phenoxyethanol and is a desirable formulation because such a formulation exhibited, when topically administered, a 40% reduction of sebum production by follicular sebaceous gland. For detailed TazSLG formulations see e.g. Tables 11, 12 and 19 in the patent application. The solid lipid nanoparticles can preferably comprise 7% glyceryl behenate (compritol 888 ATO).
A desirable carbomer in the TazSLG formulation is Carbopol 974P available from Lubrizol Advanced Materials, Inc. Carbopol 974P is a polymer of carboxypolymethylene and is a carbomer, specifically a carbomer homopolymer type B. Carbopol 974P has a viscosity, cP at 25 degrees C. of between about 29,400 to about 39,400, as determined by the Brookfield RVT method at 20 rpm, neutralized to pH 7.3 to 7.8. preferably residual monomer (i.e. free acrylic acid) is less than about 1,000 ppm.
In addition, the process for making gel vehicle component of the TazSLG described herein uses a gelling agent. The gelling agent can be, for example, acacia, alginic acid, bentonite, Carbopols® (also known as carbomers), carboxymethylcellulose. ethylcellulose, gelatin, hydroxyethylcellulose, hydroxypropyl cellulose, magnesium aluminum silicate (Veegum®), methylcellulose, poloxamers (Pluronics®), polyvinyl alcohol, sodium alginate, tragacanth, and xanthan gum. Though each gelling agent has some unique properties, there are some generalizations that can be made. For example, carbomers require a pH adjustment to create the gel after the gelling agent has been wetted in the dispersing medium. Carbomers comprise a family of Carbopol polymers. Generally used as a dry powder with a high bulk density that forms an acidic aqueous solutions (pH around 3.0) which thicken at higher pHs (around 5 or 6). Carbomers swell in aqueous solution at that pH as much as 1000 times their original volume. Their solutions range in viscosity from 0 to 80,000 centipoise (cps). Examples of carbopol gelling agents and their viscosities (within parentheses) in a 0.5% solution at pH 7.5 and at room temperature are: Carbopol® 910 (3,000-7,000), Carbopol® 934 (30,500-39,400), Carbopol® 934P (29,400-39,400), Carbopol® 940 (40,000-60,000), and Carbopol® 941 (4,000-11,000).
Patents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These patents and publications are incorporated herein by reference to the same extent as if each individual application or publication was specifically and individually incorporated herein by reference.
While the invention has been described in terms of various specific and preferred embodiments, the skilled artisan will appreciate that various modifications, substitutions, omissions, and changes may be made without departing from the spirit thereof. In particular, the indication of a particular embodiment or parameter as being “preferred” should not be construed as indicating that other embodiments and/or parameters described herein are not desirable. Accordingly, it is intended that the scope of the present invention be limited solely by the scope of the following claims, including equivalents thereof.
This application is a non-provisional application which claims the benefit of U.S. provisional application 61/932,584 entitled “Topical Dermal Compositions” filed on Jan. 28, 2014 with docket number 19349PROV (AP) which is incorporated herein by reference in its entirety and serves as the basis for a benefit and/or priority claim of the present application.
| Number | Date | Country | |
|---|---|---|---|
| 61932584 | Jan 2014 | US |
