Namenda

The molecular formula is C₁₂H₂₁N•HCl and the molecular weight is 215.76. Memantine HCl occurs as a fine white to off-white powder and is soluble in water.

NAMENDA is available as tablets or as an oral solution. NAMENDA is available for oral administration as capsule-shaped, film-coated tablets containing 5 mg and 10 mg of memantine hydrochloride. The tablets also contain the following inactive ingredients: microcrystalline cellulose/colloidal silicon dioxide, talc, croscarmellose sodium, and magnesium stearate. In addition the following inactive ingredients are also present as components of the film coat: hypromellose, titanium dioxide, polyethylene glycol 400, FD&C yellow #6 and FD&C blue #2 (5 mg tablets), and hypromellose, titanium dioxide, macrogol/polyethylene glycol 400 and iron oxide black (10 mg tablets). NAMENDA oral solution contains memantine hydrochloride in a strength equivalent to 2 mg of memantine hydrochloride in each mL. The oral solution also contains the following inactive ingredients: sorbitol solution (70%), methylparaben, propylparaben, propylene glycol, glycerin, natural peppermint flavor #104, citric acid, sodium citrate, and purified water.

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 Alzheimer's disease. Memantine is postulated to exert its therapeutic effect through its action as a 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 Alzheimer's 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 a 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

Absorption

Following 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.

Distribution

The mean volume of distribution of memantine is 9-11 L/kg and the plasma protein binding is low (45%).

Metabolism

Memantine undergoes partial hepatic metabolism. The hepatic microsomal CYP450 enzyme system does not play a significant role in the metabolism of memantine.

Elimination

Memantine is excreted predominantly (about 48%) unchanged in urine and has a 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. A 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 Populations

Gender

Following multiple dose administration of NAMENDA 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.

Elderly

The pharmacokinetics of NAMENDA in young and elderly subjects are similar.

Renal Impairment

Memantine pharmacokinetics were evaluated following single oral administration of 20 mg memantine HCl in 8 subjects with mild renal impairment (creatinine clearance, CLcr, >50 – 80 mL/min), 8 subjects with moderate renal impairment (CLcr 30 – 49 mL/min), 7 subjects with severe renal impairment (CLcr 5 – 29 mL/min) and 8 healthy subjects (CLcr > 80 mL/min) matched as closely as possible by age, weight and gender to the subjects with renal impairment. Mean AUC_0-∞ 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 Impairment

Memantine pharmacokinetics were evaluated following the administration of single oral doses of 20 mg in 8 subjects with moderate hepatic impairment (Child-Pugh Class B, score 7-9) and 8 subjects who were age-, gender-, and weight-matched to the hepatically-impaired subjects. There was no change in memantine exposure (based on C_max 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 Interactions

Use with Cholinesterase Inhibitors

Coadministration 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 a 24-week controlled clinical study in patients with moderate to severe Alzheimer's disease, the adverse event profile observed with a combination of NAMENDA and donepezil was similar to that of donepezil alone.

Effect of NAMENDA on the Metabolism of Other Drugs

In 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 NAMENDA

Memantine 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 Mechanisms

Because 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 NAMENDA 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® (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®, indicating the absence of a pharmacodynamic interaction.

Drugs Highly Bound to Plasma Proteins

Because 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.

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

There was no evidence of carcinogenicity in a 113-week oral study in mice at doses up to 40 mg/kg/day (10 times the maximum recommended human dose [MRHD] on a 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 a 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 a 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 a single dose of memantine. In a study in which rats were given daily oral doses of memantine for 14 days, the no-effect dose for neuronal necrosis was 6 times the maximum recommended human dose of 20 mg/day on a 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.

14 CLINICAL STUDIES

The effectiveness of NAMENDA as a treatment for patients with moderate to severe Alzheimer's disease was demonstrated in 2 randomized, double-blind, placebo-controlled clinical studies (Studies 1 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 a range of 50-93 years. Approximately 66% of patients were female and 91% of patients were Caucasian. A third study (Study 3), carried out in Latvia, enrolled patients with severe dementia, but did not assess cognitive function as a planned endpoint. Study Outcome Measures: In each U.S. study, the effectiveness of NAMENDA 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 NAMENDA experienced significant improvement on both measures compared to placebo.

Day-to-day function was assessed in both studies using the modified Alzheimer's disease Cooperative Study - Activities of Daily Living inventory (ADCS-ADL). The ADCS-ADL consists of a comprehensive battery of ADL questions used to measure the functional capabilities of patients. Each ADL item is rated from the highest level of independent performance to complete loss. The investigator performs the inventory by interviewing a caregiver familiar with the behavior of the patient. A subset of 19 items, including ratings of the patient's 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 a scoring range of 0 to 54, with the lower scores indicating greater functional impairment.

The ability of NAMENDA to improve cognitive performance was assessed in both studies with the Severe Impairment Battery (SIB), a multi-item 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 0 to 100, with lower scores indicating greater cognitive impairment.

Study 1 (Twenty-Eight-Week Study)

In a study of 28 weeks duration, 252 patients with moderate to severe probable Alzheimer's disease (diagnosed by DSM-IV and NINCDS-ADRDA criteria, with Mini-Mental State Examination scores ≥ 3 and ≤ 14 and Global Deterioration Scale Stages 5-6) were randomized to NAMENDA or placebo. For patients randomized to NAMENDA, treatment was initiated at 5 mg once daily and increased weekly by 5 mg/day in divided doses to a dose of 20 mg/day (10 mg twice a day).

Effects on the ADCS-ADL

Figure 1 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 NAMENDA-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), NAMENDA treatment was statistically significantly superior to placebo.

Figure 2 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 X axis. The curves show that both patients assigned to NAMENDA and placebo have a wide range of responses and generally show deterioration (a negative change in ADCS-ADL compared to baseline), but that the NAMENDA group is more likely to show a smaller decline or an improvement. (In a cumulative distribution display, a 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).

Effects on the SIB

Figure 3 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 NAMENDA-treated patients compared to the patients on placebo was 5.7 units. Using an LOCF analysis, NAMENDA treatment was statistically significantly superior to placebo.

Figure 4 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 X axis. The curves show that both patients assigned to NAMENDA and placebo have a wide range of responses and generally show deterioration, but that the NAMENDA group is more likely to show a smaller decline or an improvement.

Study 2 (Twenty-Four-Week Study)

In a study of 24 weeks duration, 404 patients with moderate to severe probable Alzheimer's disease (diagnosed by NINCDS-ADRDA criteria, with Mini-Mental State Examination scores ≥ 5 and ≤ 14) who had been treated with donepezil for at least 6 months and who had been on a stable dose of donepezil for the last 3 months were randomized to NAMENDA or placebo while still receiving donepezil. For patients randomized to NAMENDA, treatment was initiated at 5 mg once daily and increased weekly by 5 mg/day in divided doses to a dose of 20 mg/day (10 mg twice a day).

Effects on the ADCS-ADL

Figure 5 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 NAMENDA/donepezil treated patients (combination therapy) compared to the patients on placebo/donepezil (monotherapy) was 1.6 units. Using an LOCF analysis, NAMENDA/donepezil treatment was statistically significantly superior to placebo/donepezil.

Figure 6 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 X axis. The curves show that both patients assigned to NAMENDA/donepezil and placebo/donepezil have a wide range of responses and generally show deterioration, but that the NAMENDA/donepezil group is more likely to show a smaller decline or an improvement.

Effects on the SIB

Figure 7 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 NAMENDA/donepezil-treated patients compared to the patients on placebo/donepezil was 3.3 units. Using an LOCF analysis, NAMENDA/donepezil treatment was statistically significantly superior to placebo/donepezil.

Figure 8 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 X axis. The curves show that both patients assigned to NAMENDA/donepezil and placebo/donepezil have a wide range of responses, but that the NAMENDA/donepezil group is more likely to show an improvement or a smaller decline.

Study 3 (Twelve-Week Study)

In a double-blind study of 12 weeks duration, conducted in nursing homes in Latvia, 166 patients with dementia according to DSM-III-R, a Mini-Mental State Examination score of < 10, and Global Deterioration Scale staging of 5 to 7 were randomized to either NAMENDA or placebo. For patients randomized to NAMENDA, treatment was initiated at 5 mg once daily and increased to 10 mg once daily after 1 week. The primary efficacy measures were the care dependency subscale of the Behavioral Rating Scale for Geriatric Patients (BGP), a measure of day-to-day function, and a Clinical Global Impression of Change (CGI-C), a measure of overall clinical effect. No valid measure of cognitive function was used in this study. A statistically significant treatment difference at 12 weeks that favored NAMENDA over placebo was seen on both primary efficacy measures. Because the patients entered were a mixture of Alzheimer's 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 Alzheimer's 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 Alzheimer's disease, a statistically significant treatment effect favoring NAMENDA over placebo at 12 weeks was seen on both the BGP and CGI-C.

16 HOW SUPPLIED/STORAGE AND HANDLING

5 mg Tablet:

Tan, capsule-shaped, film-coated tablets with “5” debossed on one side and FL on the other.

Bottle of 60               NDC #0456-3205-60
10 x 10 Unit Dose      NDC #0456-3205-63

10 mg Tablet:

Gray, capsule-shaped, film-coated tablets with “10” debossed on one side and FL on the other.

Bottle of 60               NDC #0456-3210-60
10 x 10 Unit Dose     NDC #0456-3210-63

Titration Pack:          NDC #0456-3200-14
Blister package containing 49 tablets (28 x 5 mg and 21 x 10 mg tablets).

Oral Solution:
2 mg/mL Oral Solution (10 mg = 5 mL)
12 fl. oz. (360 mL) bottle        NDC #0456-3202-12

Store Namenda tablets and oral solution at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature].

17 PATIENT COUNSELING INFORMATION

See FDA-approved patient labeling (Patient Information and Instructions for Use).

To assure safe and effective use of NAMENDA, 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 NAMENDA. They should be warned not to use any tablets of NAMENDA that are damaged or show signs of tampering.

If a patient misses a single dose of NAMENDA, that patient should not double up on the next dose. The next dose should be taken as scheduled. If a patient fails to take NAMENDA for several days, dosing should not be resumed without consulting that patient's healthcare professional.

Patients/caregivers should be instructed on how to use the NAMENDA 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.

Manufactured for:
Forest Pharmaceuticals, Inc.
Subsidiary of Forest Laboratories, Inc.
St. Louis, MO 63045

Manufactured by:
Forest Laboratories Ireland Ltd

Licensed from Merz Pharmaceuticals GmbH

© 2005-2012 Forest Laboratories, Inc.

Patient Information

NAMENDA (Nuh-MEN-dah)

(memantine hydrochloride)

Tablets and Oral Solution

Read this Patient Information that comes with NAMENDA before you start taking it and each time you get a 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.

What is NAMENDA?

NAMENDA is a prescription medicine used for the treatment of moderate to severe dementia in people with Alzheimer's disease. NAMENDA belongs to a class of medicines called NMDA (N-methyl-D-aspartate) inhibitors.

It is not known if NAMENDA is safe and effective in children.

Who should not take NAMENDA?

Do not take NAMENDA if you are allergic to memantine or any of the ingredients in NAMENDA. See the end of this leaflet for a complete list of ingredients in NAMENDA.

What should I tell my doctor before taking NAMENDA?

Before you take NAMENDA, tell your doctor if you:

• have or have had seizures
• have or have had problems passing urine
• have or have had bladder or kidney problems
• have liver problems
• have any other medical conditions
• are pregnant or plan to become pregnant. It is not known if NAMENDA will harm your unborn baby.
• are breastfeeding or plan to breastfeed. It is not known if NAMENDA passes into your breast milk. You and your doctor should decide if you will take NAMENDA or breastfeed.

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Taking NAMENDA with certain other medicines may affect each other. Taking NAMENDA with other medicines can cause serious side effects.

Especially tell your doctor if you take:

• other NMDA antagonists such as amantadine, ketamine, and dextromethorphan
• medicines that make your urine alkaline such as carbonic anhydrase inhibitors and sodium bicarbonate

Ask your doctor or pharmacist for a list of these medicines, if you are not sure.

Know the medicines you take. Keep a list of them to show your doctor and pharmacist when you get a new medicine.

How should I take NAMENDA?

• See the step-by-step instructions for taking NAMENDA Oral Solution at the end of this Patient Information.
• Your doctor will tell you how much NAMENDA to take and when to take it.
• Your doctor may change your dose if needed.
• NAMENDA can be taken with food or without food.
• Do not use any tablets of NAMENDA that are damaged or show signs of tampering.
• If you forget to take one dose of NAMENDA, do not double up on the next dose. You should take only the next dose as scheduled.
• If you have forgotten to take NAMENDA for several days, you should not take the next dose until you talk to your doctor.
• If you take too much NAMENDA, call your doctor or poison control center at 1-800-222-1222 right away, or go to the nearest hospital emergency room.

What are the possible side effects of NAMENDA?

NAMENDA may cause side effects, including:

The most common side effects of NAMENDA include:

• dizziness
• headache
• confusion
• constipation

These are not all the possible side effects of NAMENDA. For more information, ask your doctor or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

How should I store NAMENDA?

• Store NAMENDA at room temperature between 59°F to 77°F (15°C to 30°C).

What are the ingredients in NAMENDA?

NAMENDA tablets:

Active ingredients: memantine hydrochloride

Inactive ingredients: microcrystalline cellulose/colloidal silicon dioxide, talc, croscarmellose sodium, and magnesium stearate

Inactive ingredients of tablet film coating: hypromellose, titanium dioxide, polyethylene glycol 400, FD&C yellow #6 and FD&C blue #2 (5 mg tablets), and hypromellose, titanium dioxide, macrogol/polyethylene glycol 400 and iron oxide black (10 mg tablets)

NAMENDA oral solution:

Active ingredients: memantine hydrochloride

Inactive ingredients: sorbitol solution (70%), methyl paraben, propylparaben, propylene glycol, glycerin, natural peppermint flavor #104, citric acid, sodium citrate, and purified water

Keep NAMENDA and all medicines out of the reach of children.

General information about the safe and effective use of NAMENDA.

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not take NAMENDA for a condition for which it was not prescribed. Do not give NAMENDA to other people, even if they have the same condition. It may harm them.

This Patient Information leaflet summarizes the most important information about NAMENDA. If you would like more information, talk with your doctor. You can ask your doctor or pharmacist for information about NAMENDA that was written for healthcare professionals.

For more information about NAMENDA, go to www.namenda.com, or call Forest Laboratories, Inc. at 1-800-678-1605.

INSTRUCTIONS FOR USE

NAMENDA (Nuh-MEN-dah)

(memantine hydrochloride)

Oral Solution

Directions for Using your NAMENDA Oral Solution

Read these instructions before taking NAMENDA Oral Solution and each time you get a 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.

Preparing your dose of NAMENDA Oral Solution.

You will need the following supplies:

• NAMENDA Oral Solution bottle with Child-resistant cap
• Green syringe adaptor cap with lid
• Oral dosing syringe
• Plastic tube (in plastic bag)
• Prescribing Information

This Patient Information and Instructions for Use have been approved by the U.S. Food and Drug Administration.

Manufactured for:
Forest Pharmaceuticals, Inc.
Subsidiary of Forest Laboratories, Inc.
St. Louis, MO 63045

Manufactured by:
Forest Laboratories Ireland Ltd

Licensed from Merz Pharmaceuticals GmbH

Revised October 2013