ADVERSE REACTIONS SECTION.

6 ADVERSE REACTIONS. Most common adverse reactions (>= % and greater than placebo) are dizziness, headache, confusion and constipation. (6.1)To report SUSPECTED ADVERSE REACTIONS, contact Lannett Company, Inc. at 1-844-834-0530 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.. 6.1 Clinical Trials Experience. Memantine hydrochloride was evaluated in eight double-blind placebo-controlled trials involving total of 1862 dementia (Alzheimers disease, vascular dementia) patients (940 patients treated with memantine hydrochloride and 922 patients treated with placebo) for treatment period up to 28 weeks.Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.Adverse Events Leading to DiscontinuationIn placebo-controlled trials in which dementia patients received doses of memantine hydrochloride up to 20 mg/day, the likelihood of discontinuation because of an adverse reaction was the same in the memantine hydrochloride group (10.1%) as in the placebo group (11.5%). No individual adverse reaction was associated with the discontinuation of treatment in 1% or more of memantine hydrochloride-treated patients and at rate greater than placebo.Most Common Adverse ReactionsIn double-blind placebo-controlled trials involving dementia patients, the most common adverse reactions (incidence >= 5% and higher than placebo) in patients treated with memantine hydrochloride were dizziness, headache, confusion and constipation. Table lists all adverse reactions that occurred in at least 2% of patients treated with memantine hydrochloride and at an incidence greater than placebo.Table 1: Adverse Reactions Reported in Controlled Clinical Trials in at Least 2% of Patients Receiving Memantine Hydrochloride and at Higher Frequency than Placebo-treated Patients Adverse Reaction Placebo(N 922)%Memantine Hydrochloride (N 940) Body as Whole Fatigue 2 Pain 3 Cardiovascular System Hypertension 4 Central and Peripheral Nervous System Dizziness 7 Headache 6 Gastrointestinal System Constipation 5 Vomiting 3 Musculoskeletal System Back pain 3 Psychiatric Disorders Confusion 6 Somnolence 3 Hallucination 3 Respiratory System Coughing 4 Dyspnea 2The overall profile of adverse reactions and the incidence rates for individual adverse reactions in the subpopulation of patients with moderate to severe Alzheimers disease were not different from the profile and incidence rates described above for the overall dementia population.SeizuresMemantine hydrochloride has not been systematically evaluated in patients with seizure disorder. In clinical trials of memantine hydrochloride, seizures occurred in 0.2% of patients treated with memantine hydrochloride and 0.5% of patients treated with placebo.. 6.2 Postmarketing Experience. The following adverse reactions have been identified during post-approval use of memantine. Because these reactions are reported voluntarily from population of uncertain size, it is not always possible to reliably estimate their frequency or establish causal relationship to drug exposure.These reactions include:Blood and Lymphatic System Disorders agranulocytosis, leukopenia (including neutropenia), pancytopenia, thrombocytopenia, thrombotic thrombocytopenic purpura.Cardiac Disorders cardiac failure congestive. Gastrointestinal Disorders pancreatitis.Hepatobiliary Disorders hepatitis. Psychiatric Disorders suicidal ideation.Renal and Urinary Disorders acute renal failure (including increased creatinine and renal insufficiency).Skin Disorders Stevens Johnson syndrome.

ANIMAL PHARMACOLOGY & OR TOXICOLOGY SECTION.

13.2 Animal Toxicology and/or Pharmacology. Memantine induced neuronal lesions (vacuolation and necrosis) in the multipolar and pyramidal cells in cortical layers III and IV of the posterior cingulate and retrosplenial neocortices in rats, similar to those which are known to occur in rodents administered other NMDA receptor antagonists.Lesions were seen after single dose of memantine. In study in which rats were given daily oral doses of memantine for 14 days, the no-effect dose for neuronal necrosis was times the maximum recommended human dose of 20 mg/day on mg/m2 basis.In acute and repeat-dose neurotoxicity studies in female rats, oral administration of memantine and donepezil in combination resulted in increased incidence, severity, and distribution of neurodegeneration compared with memantine alone. The no-effect levels of the combination were associated with clinically relevant plasma memantine and donepezil exposures.The relevance of these findings to humans is unknown.

CARCINOGENESIS & MUTAGENESIS & IMPAIRMENT OF FERTILITY SECTION.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility. There was no evidence of carcinogenicity in 113-week oral study in mice at doses up to 40 mg/kg/day (10 times the maximum recommended human dose [MRHD] on mg/m2 basis). There was also no evidence of carcinogenicity in rats orally dosed at up to 40 mg/kg/day for 71 weeks followed by 20 mg/kg/day (20 and 10 times the MRHD on mg/m2 basis, respectively) through 128 weeks.Memantine produced no evidence of genotoxic potential when evaluated in the in vitro S. typhimurium or E. coli reverse mutation assay, an in vitro chromosomal aberration test in human lymphocytes, an in vivo cytogenetics assay for chromosome damage in rats, and the in vivo mouse micronucleus assay. The results were equivocal in an in vitro gene mutation assay using Chinese hamster V79 cells.No impairment of fertility or reproductive performance was seen in rats administered up to 18 mg/kg/day (9 times the MRHD on mg/m2 basis) orally from 14 days prior to mating through gestation and lactation in females, or for 60 days prior to mating in males.

CLINICAL PHARMACOLOGY SECTION.

12 CLINICAL PHARMACOLOGY. 12.1 Mechanism of Action. Persistent activation of central nervous system N-methyl-D-aspartate (NMDA) receptors by the excitatory amino acid glutamate has been hypothesized to contribute to the symptomatology of Alzheimers disease. Memantine is postulated to exert its therapeutic effect through its action as low to moderate affinity uncompetitive (open-channel) NMDA receptor antagonist which binds preferentially to the NMDA receptor-operated cation channels. There is no evidence that memantine prevents or slows neurodegeneration in patients with Alzheimers disease.. 12.2 Pharmacodynamics. Memantine showed low to negligible affinity for GABA, benzodiazepine, dopamine, adrenergic, histamine and glycine receptors and for voltage-dependent Ca2+, Na+ or K+ channels. Memantine also showed antagonistic effects at the 5HT3 receptor with potency similar to that for the NMDA receptor and blocked nicotinic acetylcholine receptors with one-sixth to one-tenth the potency.In vitro studies have shown that memantine does not affect the reversible inhibition of acetylcholinesterase by donepezil, galantamine, or tacrine.. 12.3 Pharmacokinetics. AbsorptionFollowing oral administration memantine is highly absorbed with peak concentrations reached in about 3-7 hours. Memantine has linear pharmacokinetics over the therapeutic dose range. Food has no effect on the absorption of memantine.DistributionThe mean volume of distribution of memantine is 9-11 L/kg and the plasma protein binding is low (45%).MetabolismMemantine undergoes partial hepatic metabolism. The hepatic microsomal CYP450 enzyme system does not play significant role in the metabolism of memantine.EliminationMemantine is excreted predominantly (about 48%) unchanged in urine and has terminal elimination half-life of about 60-80 hours.The remainder is converted primarily to three polar metabolites which possess minimal NMDA receptor antagonistic activity: the N-glucuronide conjugate, 6-hydroxy memantine, and 1-nitroso-deaminated memantine. total of 74% of the administered dose is excreted as the sum of the parent drug and the N-glucuronide conjugate. Renal clearance involves active tubular secretion moderated by pH dependent tubular reabsorption.Pharmacokinetics in Specific PopulationsGenderFollowing multiple dose administration of memantine hydrochloride 20 mg daily, females had about 45% higher exposure than males, but there was no difference in exposure when body weight was taken into account.ElderlyThe pharmacokinetics of memantine hydrochloride in young and elderly subjects are similar.Renal ImpairmentMemantine pharmacokinetics were evaluated following single oral administration of 20 mg memantine HCl in subjects with mild renal impairment (creatinine clearance, CLcr, >50 80 mL/min), subjects with moderate renal impairment (CLcr 30 49 mL/min), subjects with severe renal impairment (CLcr - 29 mL/min) and healthy subjects (CLcr 80 mL/min) matched as closely as possible by age, weight and gender to the subjects with renal impairment. Mean AUC0- increased by 4%, 60%, and 115% in subjects with mild, moderate, and severe renal impairment, respectively, compared to healthy subjects. The terminal elimination half-life increased by 18%, 41%, and 95% in subjects with mild, moderate, and severe renal impairment, respectively, compared to healthy subjects.No dosage adjustment is recommended for patients with mild and moderate renal impairment. Dosage should be reduced in patients with severe renal impairment [see Dosage and Administration (2)].Hepatic ImpairmentMemantine pharmacokinetics were evaluated following the administration of single oral doses of 20 mg in subjects with moderate hepatic impairment (Child-Pugh Class B, score 7-9) and subjects who were age-, gender-, and weight-matched to the hepatically-impaired subjects.There was no change in memantine exposure (based on Cmax and AUC) in subjects with moderate hepatic impairment as compared with healthy subjects. However, terminal elimination half-life increased by about 16% in subjects with moderate hepatic impairment as compared with healthy subjects. No dose adjustment is recommended for patients with mild and moderate hepatic impairment. Memantine should be administered with caution to patients with severe hepatic impairment as the pharmacokinetics of memantine have not been evaluated in that population.Drug-Drug InteractionsUse with Cholinesterase InhibitorsCoadministration of memantine with the AChE inhibitor donepezil HCl did not affect the pharmacokinetics of either compound. Furthermore, memantine did not affect AChE inhibition by donepezil. In 24-week controlled clinical study in patients with moderate to severe Alzheimers disease, the adverse event profile observed with combination of memantine hydrochloride and donepezil was similar to that of donepezil alone.Effect of Memantine Hydrochloride on the Metabolism of Other DrugsIn vitro studies conducted with marker substrates of CYP450 enzymes (CYP1A2, -2A6, -2C9, -2D6, -2E1, -3A4) showed minimal inhibition of these enzymes by memantine. In addition, in vitro studies indicate that at concentrations exceeding those associated with efficacy, memantine does not induce the cytochrome P450 isozymes CYP1A2, -2C9, -2E1 and -3A4/5. No pharmacokinetic interactions with drugs metabolized by these enzymes are expected.Pharmacokinetic studies evaluated the potential of memantine for interaction with warfarin, and buproprion. Memantine did not affect the pharmacokinetics of the CYP2B6 substrate buproprion or its metabolite hydroxybuproprion. Furthermore, memantine did not affect the pharmacokinetics or pharmacodynamics of warfarin as assessed by the prothrombin INR.Effect of Other Drugs on Memantine HydrochlorideMemantine is predominantly renally eliminated, and drugs that are substrates and/or inhibitors of the CYP450 system are not expected to alter the metabolism of memantine.Drugs Eliminated via Renal MechanismsBecause memantine is eliminated in part by tubular secretion, coadministration of drugs that use the same renal cationic system, including hydrochlorothiazide (HCTZ), triamterene (TA), metformin, cimetidine, ranitidine, quinidine, and nicotine, could potentially result in altered plasma levels of both agents. However, coadministration of memantine hydrochloride and HCTZ/TA did not affect the bioavailability of either memantine or TA, and the bioavailability of HCTZ decreased by 20%. In addition, coadministration of memantine with the antihyperglycemic drug Glucovance(R) (glyburide and metformin HCl) did not affect the pharmacokinetics of memantine, metformin and glyburide. Furthermore, memantine did not modify the serum glucose lowering effect of Glucovance(R), indicating the absence of pharmacodynamic interaction.Drugs Highly Bound to Plasma ProteinsBecause the plasma protein binding of memantine is low (45%), an interaction with drugs that are highly bound to plasma proteins, such as warfarin and digoxin, is unlikely.

CLINICAL STUDIES SECTION.

14 CLINICAL STUDIES. The clinical efficacy studies described below were conducted with memantine hydrochloride tablets and not with memantine hydrochloride oral solution; however, bioequivalence of memantine hydrochloride oral solution with memantine hydrochloride tablets has been demonstrated.The effectiveness of memantine hydrochloride as treatment for patients with moderate to severe Alzheimers disease was demonstrated in randomized, double-blind, placebo-controlled clinical studies (Studies and 2) conducted in the United States that assessed both cognitive function and day to day function. The mean age of patients participating in these two trials was 76 with range of 50-93 years. Approximately 66% of patients were female and 91% of patients were Caucasian. third study (Study 3), carried out in Latvia, enrolled patients with severe dementia, but did not assess cognitive function as planned endpoint. Study Outcome Measures: In each U.S. study, the effectiveness of memantine hydrochloride was determined using both an instrument designed to evaluate overall function through caregiver-related assessment, and an instrument that measures cognition. Both studies showed that patients on memantine hydrochloride experienced significant improvement on both measures compared to placebo.Day-to-day function was assessed in both studies using the modified Alzheimers disease Cooperative Study Activities of Daily Living inventory (ADCS-ADL). The ADCS-ADL consists of comprehensive battery of ADL questions used to measure the functional capabilities of patients. Each ADL text is rated from the highest level of independent performance to complete loss. The investigator performs the inventory by interviewing caregiver familiar with the behavior of the patient. subset of 19 texts, including ratings of the patients ability to eat, dress, bathe, telephone, travel, shop, and perform other household chores has been validated for the assessment of patients with moderate to severe dementia. This is the modified ADCS-ADL, which has scoring range of to 54, with the lower scores indicating greater functional impairment.The ability of memantine hydrochloride to improve cognitive performance was assessed in both studies with the Severe Impairment Battery (SIB), multi-text instrument that has been validated for the evaluation of cognitive function in patients with moderate to severe dementia. The SIB examines selected aspects of cognitive performance, including elements of attention, orientation, language, memory, visuospatial ability, construction, praxis, and social interaction. The SIB scoring range is from to 100, with lower scores indicating greater cognitive impairment.Study (Twenty-Eight-Week Study)In study of 28 weeks duration, 252 patients with moderate to severe probable Alzheimers disease (diagnosed by DSM-IV and NINCDS-ADRDA criteria, with Mini-Mental State Examination scores >= and <= 14 and Global Deterioration Scale Stages 5-6) were randomized to memantine hydrochloride or placebo. For patients randomized to memantine hydrochloride, treatment was initiated at mg once daily and increased weekly by mg/day in divided doses to dose of 20 mg/day (10 mg twice day).Effects on the ADCS-ADLFigure shows the time course for the change from baseline in the ADCS-ADL score for patients in the two treatment groups completing the 28 weeks of the study. At 28 weeks of treatment, the mean difference in the ADCS-ADL change scores for the memantine hydrochloride-treated patients compared to the patients on placebo was 3.4 units. Using an analysis based on all patients and carrying their last study observation forward (LOCF analysis), memantine hydrochloride treatment was statistically significantly superior to placebo. Figure 1: Time course of the change from baseline in ADCS-ADL score for patients completing 28 weeks of treatment.Figure shows the cumulative percentages of patients from each of the treatment groups who had attained at least the change in the ADCS-ADL shown on the axis. The curves show that both patients assigned to memantine hydrochloride and placebo have wide range of responses and generally show deterioration (a negative change in ADCS-ADL compared to baseline), but that the memantine hydrochloride group is more likely to show smaller decline or an improvement. (In cumulative distribution display, curve for an effective treatment would be shifted to the left of the curve for placebo, while an ineffective or deleterious treatment would be superimposed upon or shifted to the right of the curve for placebo). Figure 2: Cumulative percentage of patients completing 28 weeks of double-blind treatment with specified changes from baseline in ADCS-ADL scores.Effects on the SIBFigure shows the time course for the change from baseline in SIB score for the two treatment groups over the 28 weeks of the study. At 28 weeks of treatment, the mean difference in the SIB change scores for the memantine hydrochloride-treated patients compared to the patients on placebo was 5.7 units. Using an LOCF analysis, memantine hydrochloride treatment was statistically significantly superior to placebo. Figure 3: Time course of the change from baseline in SIB score for patients completing 28 weeks of treatment.Figure shows the cumulative percentages of patients from each treatment group who had attained at least the measure of change in SIB score shown on the axis. The curves show that both patients assigned to memantine hydrochloride and placebo have wide range of responses and generally show deterioration, but that the memantine hydrochloride group is more likely to show smaller decline or an improvement.Figure 4: Cumulative percentage of patients completing 28 weeks of double-blind treatment with specified changes from baseline in SIB scores.Study (Twenty-Four-Week Study)In study of 24 weeks duration, 404 patients with moderate to severe probable Alzheimers disease (diagnosed by NINCDS-ADRDA criteria, with Mini-Mental State Examination scores >= and <= 14) who had been treated with donepezil for at least months and who had been on stable dose of donepezil for the last months were randomized to memantine hydrochloride or placebo while still receiving donepezil. For patients randomized to memantine hydrochloride, treatment was initiated at mg once daily and increased weekly by mg/day in divided doses to dose of 20 mg/day (10 mg twice day).Effects on the ADCS-ADLFigure shows the time course for the change from baseline in the ADCS-ADL score for the two treatment groups over the 24 weeks of the study. At 24 weeks of treatment, the mean difference in the ADCS-ADL change scores for the memantine hydrochloride/donepezil treated patients (combination therapy) compared to the patients on placebo/donepezil (monotherapy) was 1.6 units. Using an LOCF analysis, memantine hydrochloride/donepezil treatment was statistically significantly superior to placebo/donepezil. Figure 5: Time course of the change from baseline in ADCS-ADL score for patients completing 24 weeks of treatment.Figure shows the cumulative percentages of patients from each of the treatment groups who had attained at least the measure of improvement in the ADCS-ADL shown on the axis. The curves show that both patients assigned to memantine hydrochloride/donepezil and placebo/donepezil have wide range of responses and generally show deterioration, but that the memantine hydrochloride/donepezil group is more likely to show smaller decline or an improvement. Figure 6: Cumulative percentage of patients completing 24 weeks of double-blind treatment with specified changes from baseline in ADCS-ADL scores.Effects on the SIBFigure shows the time course for the change from baseline in SIB score for the two treatment groups over the 24 weeks of the study. At 24 weeks of treatment, the mean difference in the SIB change scores for the memantine hydrochloride/donepezil-treated patients compared to the patients on placebo/donepezil was 3.3 units. Using an LOCF analysis, memantine hydrochloride/donepezil treatment was statistically significantly superior to placebo/donepezil. Figure 7: Time course of the change from baseline in SIB score for patients completing 24 weeks of treatment.Figure shows the cumulative percentages of patients from each treatment group who had attained at least the measure of improvement in SIB score shown on the axis. The curves show that both patients assigned to memantine hydrochloride/donepezil and placebo/donepezil have wide range of responses, but that the memantine hydrochloride/donepezil group is more likely to show an improvement or smaller decline. Figure 8: Cumulative percentage of patients completing 24 weeks of double-blind treatment with specified changes from baseline in SIB scores.Study (Twelve-Week Study)In double-blind study of 12 weeks duration, conducted in nursing homes in Latvia, 166 patients with dementia according to DSM-III-R, Mini-Mental State Examination score of 10, and Global Deterioration Scale staging of to were randomized to either memantine hydrochloride or placebo. For patients randomized to memantine hydrochloride, treatment was initiated at mg once daily and increased to 10 mg once daily after week. The primary efficacy measures were the care dependency subscale of the Behavioral Rating Scale for Geriatric Patients (BGP), measure of day-to-day function, and Clinical Global Impression of Change (CGI-C), measure of overall clinical effect. No valid measure of cognitive function was used in this study. statistically significant treatment difference at 12 weeks that favored memantine hydrochloride over placebo was seen on both primary efficacy measures. Because the patients entered were mixture of Alzheimers disease and vascular dementia, an attempt was made to distinguish the two groups and all patients were later designated as having either vascular dementia or Alzheimers disease, based on their scores on the Hachinski Ischemic Scale at study entry. Only about 50% of the patients had computerized tomography of the brain. For the subset designated as having Alzheimers disease, statistically significant treatment effect favoring memantine hydrochloride over placebo at 12 weeks was seen on both the BGP and CGI-C.. fig1. fig2. fig3. fig4. fig5. fig6. fig7. fig8.

CONTRAINDICATIONS SECTION.

4 CONTRAINDICATIONS. Memantine hydrochloride is contraindicated in patients with known hypersensitivity to memantine hydrochloride or to any excipients used in the formulation.. Memantine hydrochloride is contraindicated in patients with known hypersensitivity to memantine hydrochloride or to any excipients used in the formulation. (4).

DESCRIPTION SECTION.

11 DESCRIPTION. Memantine hydrochloride is an orally active NMDA receptor antagonist. The chemical name for memantine hydrochloride is 1-amino-3,5-dimethyladamantane hydrochloride with the following structural formula:The molecular formula is C12H21NoHCl and the molecular weight is 215.76. Memantine HCl occurs as fine white to off-white powder and is soluble in water.Memantine hydrochloride oral solution contains memantine hydrochloride in strength equivalent to mg of memantine hydrochloride in each mL. The oral solution also contains the following inactive ingredients: sucralose, methylparaben, propylparaben, propylene glycol, glycerin, peppermint flavor PFC 9927, citric acid, sodium citrate, and purified water.. molec-structure.

DOSAGE & ADMINISTRATION SECTION.

2 DOSAGE AND ADMINISTRATION. The recommended starting dose of memantine hydrochloride is mg (2.5 mL) once daily. The dose should be increased in mg increments to 10 mg/day (2.5 mL twice daily), 15 mg/day (2.5 mL and mL as separate doses), and 20 mg/day (5 mL twice daily). The minimum recommended interval between dose increases is one week. The dosage shown to be effective in controlled clinical trials is 20 mg/day (5 mL twice daily).Dosing Titration Schedule Total daily dose Strength per dose (mg)Starting Dose 5mg 5mg Dose after week 10mg 5mg (first daily dose) 5mg (second daily dose) Dose after week 15mg 5mg (first daily dose) 10mg (second daily dose) Dose after week 20mg 10mg (first daily dose) 10mg (second daily dose)Memantine hydrochloride can be taken with or without food. If patient misses single dose of memantine hydrochloride, that patient should not double up on the next dose. The next dose should be taken as scheduled.If patient fails to take memantine hydrochloride for several days, dosing may need to be resumed at lower doses and retitrated as described above.Do not mix memantine hydrochloride oral solution with any other liquid. Memantine hydrochloride is administered with dosing device that comes with the drug and consists of syringe, press in bottle adaptor and other supplies patient needs to administer the drug. The supplied syringe should be used to withdraw the correct volume of oral solution and the oral solution should be slowly squirted into the corner of the patients mouth.Special PopulationsRenal ImpairmentA target dose of mg (2.5 mL) twice daily is recommended in patients with severe renal impairment (creatinine clearance of - 29 mL/min based on the Cockcroft-Gault equation).Hepatic ImpairmentMemantine hydrochloride should be administered with caution to patients with severe hepatic impairment [see Clinical Pharmacology (12.3)].. May be taken with or without food (2)Initial dose is mg (2.5 mL) once daily. Increase dose in mg increments to maintenance dose of 10 mg (5 mL) twice daily. minimum of week of treatment with the previous dose should be observed before increasing the dose. (2)Severe renal impairment: recommended dose is mg (2.5 mL) twice daily. (2). May be taken with or without food (2). Initial dose is mg (2.5 mL) once daily. Increase dose in mg increments to maintenance dose of 10 mg (5 mL) twice daily. minimum of week of treatment with the previous dose should be observed before increasing the dose. (2). Severe renal impairment: recommended dose is mg (2.5 mL) twice daily. (2).

DOSAGE FORMS & STRENGTHS SECTION.

3 DOSAGE FORMS AND STRENGTHS. Memantine hydrochloride mg/mL oral solution: clear, alcohol-free, sugar-free, and peppermint flavored.. Oral Solution: mg/mL (3).

DRUG INTERACTIONS SECTION.

7 DRUG INTERACTIONS. 7.1 Drugs that Make the Urine Alkaline. The clearance of memantine was reduced by about 80% under alkaline urine conditions at pH 8. Therefore, alterations of urine pH towards the alkaline condition may lead to an accumulation of the drug with possible increase in adverse effects. Urine pH is altered by diet, drugs (e.g. carbonic anhydrase inhibitors, sodium bicarbonate) and clinical state of the patient (e.g. renal tubular acidosis or severe infections of the urinary tract). Hence, memantine should be used with caution under these conditions.. 7.2 Use with Other N-methyl-D-aspartate (NMDA) Antagonists. The combined use of memantine hydrochloride with other NMDA antagonists (amantadine, ketamine, and dextromethorphan) has not been systematically evaluated and such use should be approached with caution.

GERIATRIC USE SECTION.

8.5 Geriatric Use. The majority of people with Alzheimers disease are 65 years and older. In the clinical studies of memantine hydrochloride the mean age of patients was approximately 76; over 90% of patients were 65 years and older, 60% were 75 years and older, and 12% were at or above 85 years of age. The efficacy and safety data presented in the clinical trial sections were obtained from these patients. There were no clinically meaningful differences in most adverse events reported by patient groups >=65 years old and <65 year old.

HOW SUPPLIED SECTION.

16 HOW SUPPLIED/STORAGE AND HANDLING. mg/mL Oral Solution12 fl. oz. (360 mL) bottle NDC 0527-1943-13Store memantine hydrochloride oral solution at 25C (77F); excursions permitted to 15-30C (59-86F) [see USP Controlled Room Temperature].

INDICATIONS & USAGE SECTION.

1 INDICATIONS AND USAGE. Memantine hydrochloride is indicated for the treatment of moderate to severe dementia of the Alzheimers type.. Memantine hydrochloride is an N-methyl-D-aspartate (NMDA) receptor antagonist indicated for the treatment of moderate to severe dementia of the Alzheimers type. (1).

INFORMATION FOR PATIENTS SECTION.

17 PATIENT COUNSELING INFORMATION. See FDA-approved patient labeling (Patient Information and Instructions for Use).To assure safe and effective use of memantine hydrochloride, the following information and instructions provided in the patient information section should be discussed with patients and caregivers.Patients/caregivers should be instructed to follow the dose titration schedule provided by their physician or healthcare professional for memantine hydrochloride.If patient misses single dose of memantine hydrochloride, that patient should not double up on the next dose. The next dose should be taken as scheduled. If patient fails to take memantine hydrochloride for several days, dosing should not be resumed without consulting that patients healthcare professional.Patients/caregivers should be instructed on how to use the memantine hydrochloride oral solution dosing device. They should be made aware of the patient instruction sheet that is enclosed with the product.Patients/caregivers should be instructed to address any questions on the usage of the solution to their physician or pharmacist.Distributed by:Lannett Company, Inc.Philadelphia, PA 1913610-1118Rev. 04/2021MG 42812.

INSTRUCTIONS FOR USE SECTION.

PATIENT INSTRUCTION FOR MEMANTINE HYDROCHLORIDE ORAL SOLUTION. Read these instructions before taking memantine hydrochloride oral solution and each time you get refill. There may be new information. This information does not take the place of talking to your doctor about your medical condition or your treatment.Follow the directions below to use your Memantine Hydrochloride Oral Solution dosing deviceIMPORTANT: Read these instructions before using Memantine Hydrochloride Oral Solution.INSTRUCTIONS FOR USEMemantine Hydrochloride (mem an teen hye droe klor ide) Oral SolutionDirections for Using your Memantine Hydrochloride Oral Solution Figure 11. Remove cap by pressing down and turning it counter-clockwise. See Figure 1.Figure 22.While holding the bottle firmly, insert plastic bottle adapter completely into neck of the open bottle. See Figure 2. Do not remove the plastic bottle adapter once it has been inserted into the neck of the bottle. Figure 3. Insert the tip of syringe firmly into opening of plastic bottle adapter. See Figure 3. Figure 4.Invert the entire unit (bottle with syringe) upside down as shown in Figure 4.5.While holding the bottle and outer barrel of syringe, pull the plunger down slowly to the level (see markings on side) that equals the dosage prescribed by your doctor. (See Figure 4) 6.Remove the syringe from the bottle and swallow the Oral Solution directly from the syringe. Do not mix with any other liquid. 7.After use, place the child-resistant cap with the plastic bottle adapter on the bottle, rinse the empty syringe by inserting the open end of the syringe into glass of water, pulling the plunger out to draw in water, and pushing the plunger in to remove the water. Allow the syringe to air dry.This Patient Information and Instructions for Use have been approved by the U.S. Food and Drug Administration.Distributed by:Lannett Company, Inc.Philadelphia, PA 1913610-1239Rev. 04/2021. pat-fig1. pat-fig2. pat-fig3. pat-fig4.

MECHANISM OF ACTION SECTION.

12.1 Mechanism of Action. Persistent activation of central nervous system N-methyl-D-aspartate (NMDA) receptors by the excitatory amino acid glutamate has been hypothesized to contribute to the symptomatology of Alzheimers disease. Memantine is postulated to exert its therapeutic effect through its action as low to moderate affinity uncompetitive (open-channel) NMDA receptor antagonist which binds preferentially to the NMDA receptor-operated cation channels. There is no evidence that memantine prevents or slows neurodegeneration in patients with Alzheimers disease.

NONCLINICAL TOXICOLOGY SECTION.

13 NONCLINICAL TOXICOLOGY. 13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility. There was no evidence of carcinogenicity in 113-week oral study in mice at doses up to 40 mg/kg/day (10 times the maximum recommended human dose [MRHD] on mg/m2 basis). There was also no evidence of carcinogenicity in rats orally dosed at up to 40 mg/kg/day for 71 weeks followed by 20 mg/kg/day (20 and 10 times the MRHD on mg/m2 basis, respectively) through 128 weeks.Memantine produced no evidence of genotoxic potential when evaluated in the in vitro S. typhimurium or E. coli reverse mutation assay, an in vitro chromosomal aberration test in human lymphocytes, an in vivo cytogenetics assay for chromosome damage in rats, and the in vivo mouse micronucleus assay. The results were equivocal in an in vitro gene mutation assay using Chinese hamster V79 cells.No impairment of fertility or reproductive performance was seen in rats administered up to 18 mg/kg/day (9 times the MRHD on mg/m2 basis) orally from 14 days prior to mating through gestation and lactation in females, or for 60 days prior to mating in males.. 13.2 Animal Toxicology and/or Pharmacology. Memantine induced neuronal lesions (vacuolation and necrosis) in the multipolar and pyramidal cells in cortical layers III and IV of the posterior cingulate and retrosplenial neocortices in rats, similar to those which are known to occur in rodents administered other NMDA receptor antagonists.Lesions were seen after single dose of memantine. In study in which rats were given daily oral doses of memantine for 14 days, the no-effect dose for neuronal necrosis was times the maximum recommended human dose of 20 mg/day on mg/m2 basis.In acute and repeat-dose neurotoxicity studies in female rats, oral administration of memantine and donepezil in combination resulted in increased incidence, severity, and distribution of neurodegeneration compared with memantine alone. The no-effect levels of the combination were associated with clinically relevant plasma memantine and donepezil exposures.The relevance of these findings to humans is unknown.

NURSING MOTHERS SECTION.

8.3 Nursing Mothers. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when memantine hydrochloride is administered to nursing mother.

OVERDOSAGE SECTION.

10 OVERDOSAGE. Signs and symptoms most often accompanying memantine overdosage in clinical trials and from worldwide marketing experience, alone or in combination with other drugs and/or alcohol, include agitation, asthenia, bradycardia, confusion, coma, dizziness, ECG changes, increased blood pressure, lethargy, loss of consciousness, psychosis, restlessness, slowed movement, somnolence, stupor, unsteady gait, visual hallucinations, vertigo, vomiting, and weakness. The largest known ingestion of memantine worldwide was 2.0 grams in patient who took memantine in conjunction with unspecified antidiabetic medications. The patient experienced coma, diplopia, and agitation, but subsequently recovered. Fatal outcome has been very rarely reported with memantine, and the relationship to memantine was unclear.Because strategies for the management of overdose are continually evolving, it is advisable to contact poison control center to determine the latest recommendations for the management of an overdose of any drug. As in any cases of overdose, general supportive measures should be utilized, and treatment should be symptomatic. Elimination of memantine can be enhanced by acidification of urine.

PACKAGE LABEL.PRINCIPAL DISPLAY PANEL.

PRINCIPAL DISPLAY PANEL. NDC 0527-1943-13Memantine Hydrochloride Oral Solution2 mg/mLRx Only360 mL (12 fl oz) 2 mg/ mL.

PEDIATRIC USE SECTION.

8.4 Pediatric Use. Safety and effectiveness in pediatric patients have not been established.

PHARMACODYNAMICS SECTION.

12.2 Pharmacodynamics. Memantine showed low to negligible affinity for GABA, benzodiazepine, dopamine, adrenergic, histamine and glycine receptors and for voltage-dependent Ca2+, Na+ or K+ channels. Memantine also showed antagonistic effects at the 5HT3 receptor with potency similar to that for the NMDA receptor and blocked nicotinic acetylcholine receptors with one-sixth to one-tenth the potency.In vitro studies have shown that memantine does not affect the reversible inhibition of acetylcholinesterase by donepezil, galantamine, or tacrine.

PHARMACOKINETICS SECTION.

12.3 Pharmacokinetics. AbsorptionFollowing oral administration memantine is highly absorbed with peak concentrations reached in about 3-7 hours. Memantine has linear pharmacokinetics over the therapeutic dose range. Food has no effect on the absorption of memantine.DistributionThe mean volume of distribution of memantine is 9-11 L/kg and the plasma protein binding is low (45%).MetabolismMemantine undergoes partial hepatic metabolism. The hepatic microsomal CYP450 enzyme system does not play significant role in the metabolism of memantine.EliminationMemantine is excreted predominantly (about 48%) unchanged in urine and has terminal elimination half-life of about 60-80 hours.The remainder is converted primarily to three polar metabolites which possess minimal NMDA receptor antagonistic activity: the N-glucuronide conjugate, 6-hydroxy memantine, and 1-nitroso-deaminated memantine. total of 74% of the administered dose is excreted as the sum of the parent drug and the N-glucuronide conjugate. Renal clearance involves active tubular secretion moderated by pH dependent tubular reabsorption.Pharmacokinetics in Specific PopulationsGenderFollowing multiple dose administration of memantine hydrochloride 20 mg daily, females had about 45% higher exposure than males, but there was no difference in exposure when body weight was taken into account.ElderlyThe pharmacokinetics of memantine hydrochloride in young and elderly subjects are similar.Renal ImpairmentMemantine pharmacokinetics were evaluated following single oral administration of 20 mg memantine HCl in subjects with mild renal impairment (creatinine clearance, CLcr, >50 80 mL/min), subjects with moderate renal impairment (CLcr 30 49 mL/min), subjects with severe renal impairment (CLcr - 29 mL/min) and healthy subjects (CLcr 80 mL/min) matched as closely as possible by age, weight and gender to the subjects with renal impairment. Mean AUC0- increased by 4%, 60%, and 115% in subjects with mild, moderate, and severe renal impairment, respectively, compared to healthy subjects. The terminal elimination half-life increased by 18%, 41%, and 95% in subjects with mild, moderate, and severe renal impairment, respectively, compared to healthy subjects.No dosage adjustment is recommended for patients with mild and moderate renal impairment. Dosage should be reduced in patients with severe renal impairment [see Dosage and Administration (2)].Hepatic ImpairmentMemantine pharmacokinetics were evaluated following the administration of single oral doses of 20 mg in subjects with moderate hepatic impairment (Child-Pugh Class B, score 7-9) and subjects who were age-, gender-, and weight-matched to the hepatically-impaired subjects.There was no change in memantine exposure (based on Cmax and AUC) in subjects with moderate hepatic impairment as compared with healthy subjects. However, terminal elimination half-life increased by about 16% in subjects with moderate hepatic impairment as compared with healthy subjects. No dose adjustment is recommended for patients with mild and moderate hepatic impairment. Memantine should be administered with caution to patients with severe hepatic impairment as the pharmacokinetics of memantine have not been evaluated in that population.Drug-Drug InteractionsUse with Cholinesterase InhibitorsCoadministration of memantine with the AChE inhibitor donepezil HCl did not affect the pharmacokinetics of either compound. Furthermore, memantine did not affect AChE inhibition by donepezil. In 24-week controlled clinical study in patients with moderate to severe Alzheimers disease, the adverse event profile observed with combination of memantine hydrochloride and donepezil was similar to that of donepezil alone.Effect of Memantine Hydrochloride on the Metabolism of Other DrugsIn vitro studies conducted with marker substrates of CYP450 enzymes (CYP1A2, -2A6, -2C9, -2D6, -2E1, -3A4) showed minimal inhibition of these enzymes by memantine. In addition, in vitro studies indicate that at concentrations exceeding those associated with efficacy, memantine does not induce the cytochrome P450 isozymes CYP1A2, -2C9, -2E1 and -3A4/5. No pharmacokinetic interactions with drugs metabolized by these enzymes are expected.Pharmacokinetic studies evaluated the potential of memantine for interaction with warfarin, and buproprion. Memantine did not affect the pharmacokinetics of the CYP2B6 substrate buproprion or its metabolite hydroxybuproprion. Furthermore, memantine did not affect the pharmacokinetics or pharmacodynamics of warfarin as assessed by the prothrombin INR.Effect of Other Drugs on Memantine HydrochlorideMemantine is predominantly renally eliminated, and drugs that are substrates and/or inhibitors of the CYP450 system are not expected to alter the metabolism of memantine.Drugs Eliminated via Renal MechanismsBecause memantine is eliminated in part by tubular secretion, coadministration of drugs that use the same renal cationic system, including hydrochlorothiazide (HCTZ), triamterene (TA), metformin, cimetidine, ranitidine, quinidine, and nicotine, could potentially result in altered plasma levels of both agents. However, coadministration of memantine hydrochloride and HCTZ/TA did not affect the bioavailability of either memantine or TA, and the bioavailability of HCTZ decreased by 20%. In addition, coadministration of memantine with the antihyperglycemic drug Glucovance(R) (glyburide and metformin HCl) did not affect the pharmacokinetics of memantine, metformin and glyburide. Furthermore, memantine did not modify the serum glucose lowering effect of Glucovance(R), indicating the absence of pharmacodynamic interaction.Drugs Highly Bound to Plasma ProteinsBecause the plasma protein binding of memantine is low (45%), an interaction with drugs that are highly bound to plasma proteins, such as warfarin and digoxin, is unlikely.

PREGNANCY SECTION.

8.1 Pregnancy. Pregnancy Category BThere are no adequate and well-controlled studies of memantine in pregnant women. Memantine hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.Memantine given orally to pregnant rats and pregnant rabbits during the period of organogenesis was not teratogenic up to the highest doses tested (18 mg/kg/day in rats and 30 mg/kg/day in rabbits, which are and 30 times, respectively, the maximum recommended human dose [MRHD] on mg/m2 basis).Slight maternal toxicity, decreased pup weights and an increased incidence of non-ossified cervical vertebrae were seen at an oral dose of 18 mg/kg/day in study in which rats were given oral memantine beginning pre-mating and continuing through the postpartum period. Slight maternal toxicity and decreased pup weights were also seen at this dose in study in which rats were treated from day 15 of gestation through the postpartum period. The no-effect dose for these effects was mg/kg, which is times the MRHD on mg/m2 basis.

RECENT MAJOR CHANGES SECTION.

RECENT MAJOR CHANGES. Dosage and Administration (2) 08/2014.

SPL UNCLASSIFIED SECTION.

5.1 Genitourinary Conditions. Conditions that raise urine pH may decrease the urinary elimination of memantine resulting in increased plasma levels of memantine [see Drug Interactions (7.1)].

USE IN SPECIFIC POPULATIONS SECTION.

8 USE IN SPECIFIC POPULATIONS. 8.1 Pregnancy. Pregnancy Category BThere are no adequate and well-controlled studies of memantine in pregnant women. Memantine hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.Memantine given orally to pregnant rats and pregnant rabbits during the period of organogenesis was not teratogenic up to the highest doses tested (18 mg/kg/day in rats and 30 mg/kg/day in rabbits, which are and 30 times, respectively, the maximum recommended human dose [MRHD] on mg/m2 basis).Slight maternal toxicity, decreased pup weights and an increased incidence of non-ossified cervical vertebrae were seen at an oral dose of 18 mg/kg/day in study in which rats were given oral memantine beginning pre-mating and continuing through the postpartum period. Slight maternal toxicity and decreased pup weights were also seen at this dose in study in which rats were treated from day 15 of gestation through the postpartum period. The no-effect dose for these effects was mg/kg, which is times the MRHD on mg/m2 basis.. 8.3 Nursing Mothers. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when memantine hydrochloride is administered to nursing mother.. 8.4 Pediatric Use. Safety and effectiveness in pediatric patients have not been established.. 8.5 Geriatric Use. The majority of people with Alzheimers disease are 65 years and older. In the clinical studies of memantine hydrochloride the mean age of patients was approximately 76; over 90% of patients were 65 years and older, 60% were 75 years and older, and 12% were at or above 85 years of age. The efficacy and safety data presented in the clinical trial sections were obtained from these patients. There were no clinically meaningful differences in most adverse events reported by patient groups >=65 years old and <65 year old.. 8.6 Renal Impairment. No dosage adjustment is needed in patients with mild or moderate renal impairment. dosage reduction is recommended in patients with severe renal impairment [see Dosage and Administration (2) and Clinical Pharmacology (12.3)].. 8.7 Hepatic Impairment. No dosage adjustment is needed in patients with mild or moderate hepatic impairment. Memantine hydrochloride should be administered with caution to patients with severe hepatic impairment [see Dosage and Administration (2) and Clinical Pharmacology (12.3)].

WARNINGS AND PRECAUTIONS SECTION.

5 WARNINGS AND PRECAUTIONS. Conditions that raise urine pH may decrease the urinary elimination of memantine, resulting in increased plasma levels of memantine. (5.1, 7.1). 5.1 Genitourinary Conditions. Conditions that raise urine pH may decrease the urinary elimination of memantine resulting in increased plasma levels of memantine [see Drug Interactions (7.1)].