Treatment of depression in certain patient populations

Abstract

This disclosure relates to administration of a combination of: 1) about 100-110 mg, about 104-106 mg, or about 105 mg of bupropion hydrochloride, or a molar equivalent amount of a free base form or another salt form of bupropion; and 2) about 40-50 mg, about 44-46 mg, or about 45 mg of dextromethorphan hydrobromide, or a molar equivalent amount of a free base form or another salt form of dextromethorphan in certain patient populations, such as patients having moderate renal impairment, patients receiving a concomitant strong CYP2D6 inhibitor, patients who are known CYP2D6 poor metabolizers, those in need of an NMDA antagonist that does not cause dissociation, and those at risk of QT prologation.

Description

SUMMARY

This disclosure relates to administration of a combination of: 1) about 100-110 mg, about 104-106 mg, or about 105 mg of bupropion hydrochloride, or a molar equivalent amount of a free base form or another salt form of dextromethorphan; and 2) about 40-50 mg, about 44-46 mg, or about 45 mg of dextromethorphan hydrobromide, or a molar equivalent amount of a free base form or another salt form of dextromethorphan in certain patient populations.

Some embodiments include a method of treating major depressive disorder in a patient having moderate renal impairment, comprising administering a daily dose of: (i) about 105 mg of bupropion hydrochloride and (ii) about 45 mg of dextromethorphan hydrobromide to a human patient who has moderate renal impairment and is experiencing major depressive disorder.

Some embodiments include a method of treating major depressive disorder in a patient receiving a concomitant strong CYP2D6 inhibitor, comprising administering a daily dose of: (i) about 105 mg of bupropion hydrochloride and (ii) about 45 mg of dextromethorphan hydrobromide to a human patient who has major depressive disorder and is receiving concomitant treatment with a strong CYP2D6 inhibitor.

Some embodiments include a method of treating major depressive disorder in a patient who is a known CYP2D6 poor metabolizer, comprising administering a daily dose of: (i) about 105 mg of bupropion hydrochloride and (ii) about 45 mg of dextromethorphan hydrobromide to a human patient who is experiencing major depressive disorder and is known to be a CYP2D6 poor metabolizer.

Some embodiments include a method of using an N-methyl D-aspartate (NMDA) receptor antagonist to treat major depressive disorder, comprising administering, no more than twice daily, a combination of 105 mg of bupropion hydrochloride and 45 mg of dextromethorphan hydrobromide to a human patient who is experiencing major depressive disorder, wherein the dextromethorphan acts as an uncompetitive antagonist of the NMDA receptor and a sigma-1 receptor agonist, and the human patient does not experience dissociation.

Some embodiments include a method of treating major depressive disorder in a human patient at risk of QT prolongation, comprising administering, no more than twice daily, a combination of 105 mg of bupropion hydrochloride and 45 mg of dextromethorphan hydrobromide to a human patient who is experiencing major depressive disorder and is at risk of QT prolongation and torsades de pointer, wherein electrocardiographic evaluation of QT interval is not conducted on the human patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the effects of renal impairment, hepatic impairment, and CYP2D6 poor metabolizer status on the pharmacokinetics of a tablet containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride.

DETAILED DESCRIPTION

As mentioned above, this disclosure relates to administration of a combination of: 1) about 100-110 mg, about 104-106 mg, or about 105 mg of bupropion hydrochloride, or a molar equivalent amount of a free base form or another salt form of dextromethorphan; and 2) about 40-50 mg, about 44-46 mg, or about 45 mg of dextromethorphan hydrobromide, or a molar equivalent amount of a free base form or another salt form of dextromethorphan. This combination is referred to for convenience herein as the “subject combination.” In every instance where the subject combination is referred to herein, the combination of 105 mg of bupropion hydrochloride and 45 mg of dextromethorphan hydrobromide is specifically contemplated.

Dextromethorphan hydrobromide is an uncompetitive NMDA receptor antagonist and A sigma-1 receptor agonist.

The chemical name of dextromethorphan hydrobromide is morphinan, 3-methoxy-17-methyl-, (9a, 13a, 14a), hydrobromide monohydrate. Dextromethorphan hydrobromide has the empirical formula C₁₈H₂₅NO·HBr·H₂O and a molecular weight of 370.33. The structural formula is:

Dextromethorphan hydrobromide powder is white or almost white, crystalline, and sparingly soluble in water.

Bupropion hydrochloride is an aminoketone and CYP450 2D6 inhibitor.

The chemical name of bupropion hydrochloride is: (±)-1-(3-chlorophenyl)-2-[(1,1-dimethylethyl)amino]-1-propanone hydrochloride. Bupropion hydrochloride has the empirical formula C₁₃H₁₈ClNO·HCl and a molecular weight of 276.2. The structural formula is:

Bupropion hydrochloride powder is white and highly soluble in water.

The subject combination may be contained in an oral dosage form, including a tablet, such as an extended-release tablet. In some embodiments, the subject combination is contained in a dosage form for oral administration and is available as round bilayer tablets.

In some embodiments, each tablet containing the subject combination contains 45 mg of dextromethorphan hydrobromide in an immediate-release formulation. In some embodiments, each tablet of the subject combination contains 105 mg of bupropion hydrochloride in an extended-release formulation. In some embodiments, each tablet of the subject combination contains 45 mg of dextromethorphan hydrobromide in an immediate-release formulation and 105 mg of bupropion hydrochloride in an extended-release formulation.

In some embodiments, a tablet containing the subject combination contains 1-cysteine hydrochloride monohydrate. In some embodiments, a tablet containing the subject combination contains carbomer homopolymer. In some embodiments, a tablet containing the subject combination contains microcrystalline cellulose. In some embodiments, a tablet containing the subject combination contains colloidal silicon dioxide. In some embodiments, a tablet containing the subject combination contains crospovidone. In some embodiments, a tablet containing the subject combination contains stearic acid. In some embodiments, a tablet containing the subject combination contains magnesium stearate.

In some embodiments, a tablet containing the subject combination contains the following inactive ingredients: 1-cysteine hydrochloride monohydrate, carbomer homopolymer, microcrystalline cellulose, colloidal silicon dioxide, crospovidone, stearic acid, and magnesium stearate.

In some embodiments, the starting dosage of the subject combination is 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride in one tablet that is administered once daily in the morning. In some embodiments, after 3 days, the dosage is increased to one tablet (or one dosage form containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride) twice daily, e.g., given at least 8 hours apart. In some embodiments, no more than two doses containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride are administered in the same day.

The subject combination may be administered orally with or without food. In some embodiments, the tablets are swallowed whole, and not crushed, divided, or chewed.

Patients having renal impairment may require special dosing. In some embodiments, the recommended dosage of the subject combination for patients with moderate renal impairment (estimated glomerular filtration rate (eGFR) or glomerular filtration rate (GFR) of 30 to 59 mL/minute/1.73 m²) is a daily dose of 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride, or a molar equivalent amount of another form of dextromethorphan and/or bupropion, such as administration of one tablet (or one dosage form containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride) once daily, such as one tablet or other oral dosage form daily in the morning.

Patients who are concomitantly using the subject combination with strong CYP2D6 inhibitors may require special dosing. Concomitant use of the subject combination with a strong CYP2D6 inhibitor increases plasma concentrations of dextromethorphan. In some embodiments, the recommended dosage of the subject combination when coadministered with a strong CYP2D6 inhibitor is one tablet (or one dosage form containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride) once daily, such as one tablet or other oral dosage form daily in the morning. In some embodiments, the patients are monitored for adverse reactions potentially attributable to dextromethorphan, such as somnolence and dizziness.

Patients who are known CYP2D6 poor metabolizers (PMs) may require special dosing. In some embodiments, the recommended dosage for patients known to be poor CYP2D6 metabolizers is one tablet (or one dosage form containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride) once daily, such as one tablet or other oral dosage form daily in the morning.

Special precautions may be required when switching a patient to or from a monoamine oxidase inhibitor (MAOI) antidepressant to the subject combination. In some embodiments, at least 14 days must elapse between discontinuation of an MAOI intended to treat depression and initiation of therapy with the subject combination. Conversely, in some embodiments, at least 14 days must be allowed after stopping the subject combination before starting an MAOI antidepressant.

In the subject combination, bupropion inhibits the metabolism of dextromethorphan via CYP2D6. Dextromethorphan, when co-administered with bupropion, displays nonlinear pharmacokinetics at steady state, with greater than dose-proportional changes in AUC and C_max for varying doses of dextromethorphan (30 to 60 mg) and less than dose-proportional changes for varying doses of bupropion (75 to 150 mg).

Steady state plasma concentrations of dextromethorphan and bupropion when given as the subject combination are achieved within 8 days. The accumulation ratios for dextromethorphan at steady state are about 20 and about 32, respectively based on C_max and AUC_0-12. The accumulation ratios for bupropion at steady state are 1.1 and 1.5, respectively based on C_max and AUC_0-12.

After administration of the subject combination, the median T_max of dextromethorphan is about 3 hours and the median T_max of bupropion is about 2 hours. The C_max of hydroxybupropion metabolite occurs approximately 3 hours post-dose and is approximately 14 times the peak level of bupropion. The AUC_0-12 hydroxybupropion is about 19 times that of bupropion. The C_max of the erythrohydroxybupropion and threohydroxybupropion metabolites occurs approximately 4 hours post-dose and is approximately equal to and about 5 times that of bupropion, respectively. The AUC_0-12 values of erythrohydroxybupropion and threohydroxybupropion are about 1.2 and about 7 times that of bupropion, respectively.

The subject combination can be taken with or without food. Dextromethorphan C_max and AUC_0-12 were unchanged and decreased by 14%, respectively, and bupropion C_max and AUC_0-12 were increased by 3% and 6%, respectively, when the subject combination was administered with food.

The plasma protein binding of dextromethorphan is approximately 60-70% and bupropion is 84%. The extent of protein binding of the hydroxybupropion metabolite is similar to that for bupropion; whereas the extent of protein binding of the threohydrobupropion metabolite is about half that seen with bupropion.

Following 8 days of administration of the subject combination in extensive metabolizers, the mean elimination half-life of dextromethorphan was increased approximately 3-fold to about 22 hours, as compared to dextromethorphan given without bupropion.

The mean elimination half-life of dextromethorphan and bupropion was 22 hours and 15 hours, respectively. The apparent elimination half-life of hydroxybupropion, erythrohydroxybuporpion and threohydroxybupropion metabolites were approximately 35, 44 and 33 hours, respectively.

Esketamine is a non-competitive NMDA receptor antagonist indicated, in conjunction with an oral antidepressant, for the treatment of treatment-resistant depression in adults. Treatment of treatment-resistant depression carries a risk of dissociation. The label for esketamine states that because of the risks of sedation and dissociation, patients must be monitored for at least 2 hours at each treatment session, followed by an assessment to determine when the patient is considered clinically stable and ready to leave the healthcare setting.

Dissociation includes: delusional perception; depersonalization/derealization disorder; derealization; diplopia; dissociation; dysesthesia; feeling cold; feeling hot; feeling of body temperature change; hallucination; hallucination, auditory; hallucination, visual; hyperacusis; illusion; ocular discomfort; oral dysesthesia; paranesthesia; paranesthesia oral; pharyngeal paranesthesia; photophobia; time perception altered; tinnitus; vision blurred; visual impairment.

The subject combination is a combination of dextromethorphan, an uncompetitive N-methyl D-aspartate (NDMA) receptor antagonist and sigma-1 receptor agonist, and bupropion, an aminoketone and CYP450 2D6 inhibitor, indicated for the treatment of major depressive disorder (MDD) in adults. Unlike esketamine, the subject combination can be administered as a without dissociation or dissociative events. In some embodiments, the patient is not monitored for dissociation after the subject combination is administered.

Unlike the combination of quinidine and dextromethorphan, at a dose of a combination of 105 mg of bupropion hydrochloride and 45 mg of dextromethorphan hydrobromide given twice a day, the subject combination does not prolong the QT interval to any clinically relevant extent. Thus, for a human patient who is experiencing major depressive disorder and is at risk of QT prolongation and torsades de pointer, electrocardiographic evaluation of QT interval is not typically conducted on the human patient.

The subject combination may be used for adjunctive treatment of major depressive disorder or depression.

In addition to major depressive disorder, the subject combination may be used to treat other diseases in conditions in the patient populations or circumstances described herein. For example, the subject combination may be used to treat pain or a neurological disorder. Examples of neurological disorders that may be treated with the subject combination include, but are not limited to: affective disorders, psychiatric disorders, cerebral function disorders, movement disorders, dementias, motor neuron diseases, neurodegenerative diseases, seizure disorders, and headaches.

Affective disorders that may be treated by the subject combination include, but are not limited to, depression, major depression, treatment resistant depression, treatment resistant bipolar depression, bipolar disorders including cyclothymia, seasonal affective disorder, mood disorders, chronic depression (dysthymia), psychotic depression, postpartum depression, premenstrual dysphoric disorder (PMDD), situational depression, atypical depression, mania, anxiety disorders, attention deficit disorder (ADD), attention deficit disorder with hyperactivity (ADDH), and attention deficit/hyperactivity disorder (AD/HD), bipolar and manic conditions, obsessive-compulsive disorder, bulimia, obesity or weight-gain, narcolepsy, chronic fatigue syndrome, premenstrual syndrome, substance addiction or abuse, nicotine addiction, psycho-sexual dysfunction, pseudobulbar affect, and emotional lability.

Depression may be manifested by depressive symptoms. These symptoms may include psychological changes such as changes in mood, feelings of intense sadness, despair, mental slowing, loss of concentration, pessimistic worry, agitation, anxiety, irritability, guilt, anger, feelings of worthlessness, reckless behavior, suicidal thoughts, or attempts, and/or self-deprecation. Physical symptoms of depression may include insomnia, anorexia, appetite loss, weight loss, weight gain, decreased energy and libido, fatigue, restlessness, aches, pains, headaches, cramps, digestive issues, and/or abnormal hormonal circadian rhythms.

Psychiatric disorders that may be treated by the subject combination, include, but are not limited to, anxiety disorders, including but not limited to, phobias, generalized anxiety disorder, social anxiety disorder, panic disorder, agoraphobia, obsessive-compulsive disorder, and post-traumatic stress disorder (PTSD); mania, manic depressive illness, hypomania, unipolar depression, depression, stress disorders, somatoform disorders, personality disorders, psychosis, schizophrenia, delusional disorder, schizoaffective disorder, schizotypy, aggression, aggression in Alzheimer's disease, agitation, and agitation in Alzheimer's disease. Alzheimer's disease may also be referred to as dementia of the Alzheimer's type. Other neurobehavioral symptoms of Alzheimer's disease that may be treated include disinhibition and apathy.

Agitation in Alzheimer's disease occurs as the disease progresses. Agitation may present itself as inappropriate verbal, emotional, and/or physical behaviors. Inappropriate behaviors may include, but are not limited to, incoherent babbling, inappropriate emotional response, demands for attention, threats, irritability, frustration, screaming, repetitive questions, mood swings, cursing, abusive language, physical outbursts, emotional distress, restlessness, shredding, sleeping disturbances, delusions, hallucinations, pacing, wandering, searching, rummaging, repetitive body motions, hoarding, shadowing, hitting, scratching, biting, combativeness, hyperactivity, and/or kicking.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, and behavioral and psychological symptoms including agitation. AD is the most common form of dementia and afflicts an estimated 6 million individuals in the United States, a number that is anticipated to increase to approximately 14 million by 2050. Agitation is reported in up to 70% of patients with AD and is characterized by emotional distress, aggressive behaviors, disruptive irritability, and disinhibition. Managing agitation is a priority in AD. Agitation in patients with AD has been associated with increased caregiver burden, decreased functioning, accelerated cognitive decline, earlier nursing home placement, and increased mortality. There are currently no therapies approved by the FDA for the treatment of agitation in patients with AD.

Neurobehavioral symptoms have been known to appear during dementia and may be treated by the combination. Caregivers or families may feel more overwhelmed by patients' behavioral/psychological symptoms than by their cognitive impairment. Common forms of the syndrome are Alzheimer's disease, vascular dementia, dementia with Lewy bodies (abnormal aggregates of protein that develop inside nerve cells), and a group of diseases that contribute to frontotemporal dementia (degeneration of the frontal lobe of the brain). The symptoms that dementia patients have are similar to those of psychiatric disorders, but some are slightly different from each other. Neurobehavioral symptoms associated with dementia include depression, apathy, agitation, disinhibition, hallucinations, delusions, psychosis, impulsiveness, aggressiveness, compulsion, excessive sex drive, and personality disorders. Neurobehavioral symptoms such as disinhibition may also be found in other conditions such as traumatic brain injury.

Agitation in patients with Alzheimer's disease may be assessed using the Cohen Mansfield Agitation Inventory or CMAI. The CMAI assesses various behaviors including, Hitting (including self), Kicking, Grabbing onto people, Pushing, Throwing things, Biting, Scratching, Spitting, Hurting self or others, Tearing things or destroying property, Making physical sexual advances, Pacing, aimless wandering, Inappropriate dress or disrobing, Trying to get to a different place, Intentional falling, Eating/drinking inappropriate substances, Handling things inappropriately, Hiding things, Hoarding things, Performing repetitive mannerisms, General restlessness, Screaming, Making verbal sexual advances, Cursing or verbal aggression, Repetitive sentences or questions, Strange noises (weird laughter or crying), Complaining, Negativism, Constant unwarranted request for attention or help.

Schizophrenia may be treated by the combination including positive symptoms and/or negative symptoms of schizophrenia, or residual symptoms of schizophrenia. Other conditions that may treated include intermittent explosive disorder.

Cerebral function disorders that may be treated by the subject combination include, but are not limited to, disorders involving intellectual deficits such as senile dementia, Alzheimer's type dementia, memory loss, amnesia/amnestic syndrome, epilepsy, disturbances of consciousness, coma, lowering of attention, speech disorders, voice spasms, Parkinson's disease, Lennox-Gastaut syndrome, autism, hyperkinetic syndrome, and schizophrenia. Cerebral function disorders also include disorders caused by cerebrovascular diseases including, but not limited to, stroke, cerebral infarction, cerebral bleeding, cerebral arteriosclerosis, cerebral venous thrombosis, head injuries, and the like where symptoms include disturbance of consciousness, senile dementia, coma, lowering of attention, and speech disorders.

Substance addiction abuse that may be treated by the subject combination includes, but is not limited to, drug dependence, addiction to cocaine, psychostimulants (e.g., crack, cocaine, speed, meth), nicotine, alcohol, opioids, anxiolytic and hypnotic drugs, cannabis (marijuana), amphetamines, hallucinogens, phencyclidine, volatile solvents, and volatile nitrites. Nicotine addiction includes nicotine addiction of all known forms, such as smoking cigarettes, cigars and/or pipes, e-cigarettes or vaping, and addiction to chewing tobacco.

Movement disorders that may be treated by the subject combination include, but are not limited to, akathisia, akinesia, associated movements, athetosis, ataxia, ballismus, hemiballismus, bradykinesia, cerebral palsy, chorea, Huntington's disease, Huntington's disease chorea, rheumatic chorea, Sydenham's chorea, dyskinesia, tardive dyskinesia, dystonia, blepharospasm, spasmodic torticollis, dopamine-responsive dystonia, Parkinson's disease, restless legs syndrome (RLS), tremor, essential tremor, and Tourette's syndrome, and Wilson's disease.

Dementias that may be treated by the subject combination include, but are not limited to, Alzheimer's disease, Parkinson's disease, vascular dementia, dementia with Lewy bodies, mixed dementia, fronto-temporal dementia, Creutzfeldt-Jakob disease, normal pressure hydrocephalus, Huntington's disease, Wernicke-Korsakoff Syndrome, and Pick's disease.

Motor neuron diseases that may be treated by the subject combination include, but are not limited to, amyotrophic lateral sclerosis (ALS), progressive bulbar palsy, primary lateral sclerosis (PLS), progressive muscular atrophy, post-polio syndrome (PPS), spinal muscular atrophy (SMA), spinal motor atrophies, Tay-Sach's disease, Sandoff disease, and hereditary spastic paraplegia.

Neurodegenerative diseases that may be treated the subject combination include, but are not limited to, Alzheimer's disease, prion-related diseases, cerebellar ataxia, spinocerebellar ataxia (SCA), spinal muscular atrophy (SMA), bulbar muscular atrophy, Friedrich's ataxia, Huntington's disease, Lewy body disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), multiple sclerosis (MS), multiple system atrophy, Shy-Drager syndrome, corticobasal degeneration, progressive supranuclear palsy, Wilson's disease, Menkes disease, adrenoleukodystrophy, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), muscular dystrophies, Charcot-Marie-Tooth disease (CMT), familial spastic paraparesis, neurofibromatosis, olivopontine cerebellar atrophy or degeneration, striatonigral degeneration, Guillain-Barré syndrome, and spastic paraplesia.

Seizure disorders that may be treated by the subject combination include, but are not limited to, epileptic seizures, nonepileptic seizures, epilepsy, febrile seizures; partial seizures including, but not limited to, simple partial seizures, Jacksonian seizures, complex partial seizures, and epilepsia partialis continua; generalized seizures including, but not limited to, generalized tonic-clonic seizures, absence seizures, atonic seizures, myoclonic seizures, juvenile myoclonic seizures, and infantile spasms; and status epilepticus.

Types of headaches that may be treated by the subject combination include, but are not limited to, migraine, tension, and cluster headaches.

Other neurological disorders that may be treated by the subject combination include, Rett Syndrome, autism, tinnitus, disturbances of consciousness disorders, sexual dysfunction, intractable coughing, narcolepsy, cataplexy; voice disorders due to uncontrolled laryngeal muscle spasms, including, but not limited to, abductor spasmodic dysphonia, adductor spasmodic dysphonia, muscular tension dysphonia, and vocal tremor; diabetic neuropathy, chemotherapy-induced neurotoxicity, such as methotrexate neurotoxicity; incontinence including, but not limited, stress urinary incontinence, urge urinary incontinence, and fecal incontinence; and erectile dysfunction.

In some embodiments, the subject combination may be used to treat pain, joint pain, pain associated with sickle cell disease, pseudobulbar affect, depression (including treatment resistant depression), disorders related to memory and cognition, schizophrenia, Parkinson's disease, amyotrophic lateral sclerosis (ALS), Rhett's syndrome, seizures, cough (including chronic cough), etc.

In some embodiments, the subject combination may be administered orally to relieve musculoskeletal pain including low back pain, and pain associated with rheumatoid arthritis, juvenile rheumatoid arthritis, osteoarthritis, erosive osteoarthritis, sero-negative (non-rheumatoid) arthropathies, non-articular rheumatism, peri-articular disorders, axial spondyloarthritis including ankylosing spondylitis, Paget's disease, fibrous dysplasia, SAPHO syndrome, transient osteoarthritis of the hip, vertebral crush fractures, osteoporosis, etc.

In some embodiments, the subject combination may be administered to relieve inflammatory pain including musculoskeletal pain, arthritis pain, and complex regional pain syndrome.

Arthritis refers to inflammatory joint diseases that can be associated with pain. Examples of arthritis pain include pain associated with osteoarthritis, erosive osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, sero-negative (non-rheumatoid) arthropathies, non-articular rheumatism, peri-articular disorders, neuropathic arthropathies including Charcot's foot, axial spondyloarthritis including ankylosing spondylitis, and SAPHO syndrome.

In some embodiments, the subject combination is used to treat chronic musculoskeletal pain.

In some embodiments, the subject composition may be administered to relieve complex regional pain syndrome, such as complex regional pain syndrome type I (CRPS-I), complex regional pain syndrome type II (CRPS-II), CRPS-NOS, or another type of CRPS. CRPS is a type of inflammatory pain. CRPS can also have a neuropathic component. Complex regional pain syndrome is a debilitating pain syndrome. It is characterized by severe pain in a limb that can be accompanied by edema, and autonomic, motor, and sensory changes.

In some embodiments, the subject composition may be administered orally to relieve neuropathic pain.

Examples of neuropathic pain include pain due to diabetic peripheral neuropathy or diabetic peripheral neuropathic pain, post-herpetic neuralgia, trigeminal neuralgia, monoradiculopathies, phantom limb pain, central pain, pain due to multiple sclerosis, etc. Other causes of neuropathic pain include cancer-related pain, lumbar nerve root compression, spinal cord injury, post-stroke pain, central multiple sclerosis pain, HIV-associated neuropathy, and radio- or chemo-therapy associated neuropathy, etc.

In some embodiments, the subject composition may be administered to relieve fibromyalgia.

The term “treating”, or “treatment” includes the diagnosis, cure, mitigation, treatment, or prevention of disease in man or other animals, or any activity that otherwise affects the structure or any function of the body of man or other animals.

A subject combination may be used to treat any disease or condition identified as treatable by the combination of bupropion and dextromethorphan in any of the following U.S. Pat. Nos. 8,569,328, 9,168,234, 9,198,905, 9,205,083, 9,238,032, 9,278,095, 9,314,462, 9,370,513, 9,375,429, 9,408,815, 9,421,176, 9,457,023, 9,457,025, 9,474,731, 9,486,450, 9,700,528, 9,700,553, 9,707,191, 9,763,932, 9,861,595, 9,867,819, 9,968,568, 10,058,518, 10,064,857, 10,080,727, 10,092,560, 10,092,561, 10,105,327, 10,105,361, 10,251,879, 10,463,634, 10,512,643, 10,548,857, 10,596,167, 10,772,850, 10,780,064, 10,780,066, 10,786,469, 10,786,496, 10,799,497, 10,806,710, 10,864,209, 10,874,663, 10,874,664, 10,874,665, 10,881,624, 10,881,657, 10,894,046, 10,894,047, 10,898,453, all of which are incorporated by reference herein in their entireties for their disclosure of diseases that may be treated by a combination of bupropion and dextromethorphan, including specific embodiments and combinations described therein.

Example 1

In a study of the subject combination in 7 subjects with moderate (GFR 30-60 mL/min) renal impairment compared to 6 matched controls with normal renal function (matched in gender, age, and weight range to impaired subjects), both dextromethorphan and bupropion exposures increased by approximately 2-fold and clearances were reduced by 50%.

Example 2

Approximately 7 to 10% of Caucasians and 3 to 8% of African Americans lack the capacity to metabolize CYP2D6 substrates and are classified as poor metabolizers. In 3 poor metabolizers the pharmacokinetics of the subject combination resulted in an approximate 3-fold and 3.4-fold increase in dextromethorphan C_max and AUC_0-12, respectively, compared to extensive metabolizers. An exploration of steady state pharmacokinetic data in 12 poor metabolizers treated with the subject combination in efficacy trials showed plasma concentrations of dextromethorphan that were generally higher than exposures for non-poor metabolizers.

Example 3

Co-administration of the SSRI paroxetine and the subject combination was studied in 29 healthy volunteers. Paroxetine increased the overall exposure of dextromethorphan by 2.5-fold and had no effect on bupropion. The overall exposure of paroxetine was increased by 1.2-fold when co-administered with the subject combination. Based on these results, when the subject combination is prescribed with drugs that inhibit CYP2D6, the subject combination should be dosed once daily. Use caution when administering the subject combination in conjunction with drugs which are extensively metabolized via CYP2D6.

Example 4

The properties of a tablet containing a combination of dextromethorphan hydrobromide, which is an uncompetitive NMDA receptor antagonist and sigma-1 receptor agonist, and bupropion hydrochloride, which is an aminoketone and CYP450 2D6 inhibitor, were studied.

The tablets are for oral administration and are round bilayer tablets. Each tablet contains 45 mg dextromethorphan hydrobromide (equivalent to 32.98 mg of the dextromethorphan free base) in an immediate-release formulation and 105 mg bupropion hydrochloride (equivalent to 91.14 mg of the bupropion free base) in an extended-release formulation. Each tablet contains the following inactive ingredients: carbomer homopolymer, colloidal silicon dioxide, crospovidone, glyceryl monocaprylocaprate, 1-cysteine hydrochloride monohydrate, magnesium stearate, microcrystalline cellulose, polyvinyl alcohol, red iron oxide, sodium lauryl sulfate, stearic acid, talc, titanium dioxide, and/or yellow iron oxide.

The effects of renal impairment, hepatic impairment, and CYP2D6 poor metabolizer status on the exposure to a tablet containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride are summarized in FIG. 1

Results depicted in FIG. 1 are based on plasma concentrations in human patients after 8 days of twice daily dosing of a tablet containing 45 mg of dextromethorphan hydrobromide and 105 mg of bupropion hydrochloride. Data are GMRs and 90% Cls. Reference used are the matched healthy subjects for renal and hepatic impairment studies, and extensive or ultra-extensive CYP2D6 metabolizers. AUC represents the area under the plasma concentration-time curve from zero to 12 hours; BUP represents bupropion; CI is confidence interval; C_max is maximum plasma concentration; DM represents dextromethorphan; GMRs represents geometric mean ratios; PK represents pharmacokinetics.

For patients having moderate renal impairment, a 2.21-fold increase in dextromethorphan AUC_0-12, a 2.10-fold increase in dextromethorphan C_max, a 1.80-fold increase in bupropion AUC_0-12, and a 1.87-fold increase in bupropion C_max were observed.

Based upon these results, dosage adjustment is recommended in patients known to have moderate renal impairment because these patients have higher dextromethorphan and bupropion concentrations than patients with healthy renal function. The recommended total daily dose for patients known to have moderate renal impairment is about 45 mg of dextromethorphan hydrobromide and about 105 mg of bupropion hydrochloride (e.g., one tablet containing about 45 mg of dextromethorphan hydrobromide and about 105 mg of bupropion hydrochloride for administration once daily, such as in the morning), or an equivalent dose of another form dextromethorphan and/or bupropion.

Claims

1. A method of treating major depressive disorder in a human patient who has moderate renal impairment, comprising administering once daily, by mouth, one tablet containing about 105 mg of bupropion hydrochloride and about 45 mg of dextromethorphan hydrobromide to the human patient who has moderate renal impairment and is experiencing major depressive disorder, wherein the dextromethorphan hydrobromide is in an immediate-release formulation, wherein the bupropion hydrochloride is in an extended-release formulation, and wherein the tablet is a bilayer tablet.

2. A method of treating major depressive disorder in a human patient who has moderate renal impairment, comprising administering once daily, by mouth, one tablet containing about 105 mg of bupropion hydrochloride and about 45 mg of dextromethorphan hydrobromide to the human patient who has moderate renal impairment and is experiencing major depressive disorder, wherein the dextromethorphan hydrobromide is in an immediate-release formulation, wherein the bupropion hydrochloride is in an extended-release formulation, and wherein the Tmax of dextromethorphan is about 3 hours.

3. The method of claim 2, wherein steady state plasma concentrations of dextromethorphan and bupropion are achieved within 8 days, and wherein the accumulation ratio for dextromethorphan at steady state is about 20 based on the Cmax.

4. The method of claim 2, wherein steady state plasma concentrations of dextromethorphan and bupropion are achieved within 8 days, and wherein the accumulation ratio for dextromethorphan is about 32 based on the AUC0-12.

5. The method of claim 2, wherein the once-daily administration avoids the human patient having an about 2.2-fold increase in AUC0-12 of dextromethorphan as compared to the AUC0-12 of dextromethorphan that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.

6. The method of claim 2, wherein the once-daily administration avoids the patient having an about 2.1-fold increase in Cmax of dextromethorphan as compared to the Cmax of dextromethorphan that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.

7. The method of claim 2, wherein the once-daily administration avoids the human patient having an about 1.8-fold increase in AUC0-12 of bupropion as compared to the AUC0-12 of bupropion that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.

8. The method of claim 2, wherein the once-daily administration avoids the patient having an about 1.9-fold increase in Cmax of bupropion as compared to the Cmax of bupropion that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.

9. A method of treating major depressive disorder in a human patient who has moderate renal impairment, comprising administering a daily dose of: (i) about 105 mg of bupropion hydrochloride and (ii) about 45 mg of dextromethorphan hydrobromide to the human patient who has moderate renal impairment and is experiencing major depressive disorder, and wherein the human patient has an estimated glomerular filtration rate that is between about 30 mL/min/1.72 m2 and 59 mL/min/1.72 m2.

10. The method of claim 9, wherein the administering is achieved by once daily administration, by mouth, of one tablet containing about 105 mg of bupropion hydrochloride and about 45 mg of dextromethorphan hydrobromide.

11. The method of claim 10, wherein the dextromethorphan hydrobromide is in an immediate-release formulation.

12. The method of claim 11, wherein the bupropion hydrochloride is in an extended-release formulation.

13. The method of claim 12, wherein the tablet is a bilayer tablet.

14. The method of claim 12, wherein the Tmax of dextromethorphan is about 3 hours.

15. The method of claim 12, wherein steady state plasma concentrations of dextromethorphan and bupropion are achieved within 8 days, and wherein the accumulation ratio for dextromethorphan at steady state is about 20 based on the Cmax.

16. The method of claim 12, wherein steady state plasma concentrations of dextromethorphan and bupropion are achieved within 8 days, and wherein the accumulation ratio for dextromethorphan at steady state is about 32 based on the AUC0-12.

17. The method of claim 12, wherein the once-daily administration avoids the human patient having an about 2.2-fold increase in AUC0-12 of dextromethorphan as compared to the AUC0-12 of dextromethorphan that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.

18. The method of claim 12, wherein the once-daily administration avoids the patient having an about 2.1-fold increase in Cmax of dextromethorphan as compared to the Cmax of dextromethorphan that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.

19. The method of claim 12, wherein the once-daily administration avoids the human patient having an about 1.8-fold increase in AUC0-12 of bupropion as compared to the AUC0-12 of bupropion that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.

20. The method of claim 12, wherein the once-daily administration avoids the patient having an about 1.9-fold increase in Cmax of bupropion as compared to the Cmax of bupropion that would result from twice daily administration of the tablet for 8 days to a human patient who has no renal impairment.