MEMANTINE HYDROCHLORIDE

Memantine hydrochloride tablets, USP are 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 C12H21N•HCl and the molecular weight is 215.76. Memantine hydrochloride occurs as a fine white to off-white powder and is soluble in water. Memantine hydrochloride tablets, USP are available for oral administration as capsule-shaped, film-coated tablets containing 5 mg and 10 mg of memantine hydrochloride, USP. The tablets also contain the following inactive ingredients: microcrystalline cellulose, croscarmellose sodium, colloidal silicon dioxide, and magnesium stearate. In addition the following inactive ingredients are also present as components of the film coat: hypromellose, titanium dioxide, macrogol/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). structure

INDICATIONS & USAGE Memantine hydrochloride tablets, USP are an N-methyl-D-aspartate (NMDA) receptor antagonist indicated for the treatment of moderate to severe dementia of the Alzheimer's type. Memantine hydrochloride tablets, USP are an N-methyl-D-aspartate (NMDA) receptor antagonist indicated for the treatment of moderate to severe dementia of the Alzheimer's type. ( 1 )

DOSAGE & ADMINISTRATION The recommended starting dose of memantine hydrochloride is 5 mg once daily. The dose should be increased in 5 mg increments to 10 mg/day (5 mg twice daily), 15 mg/day (5 mg and 10 mg as separate doses), and 20 mg/day (10 mg 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. Memantine hydrochloride can be taken with or without food. If a patient misses a single dose of memantine hydrochloride, that patient should not double up on the next dose. The next dose should be taken as scheduled. If a patient fails to take memantine hydrochloride for several days, dosing may need to be resumed at lower doses and retitrated as described above. Specific Populations Renal Impairment A target dose of 5 mg twice daily is recommended in patients with severe renal impairment (creatinine clearance of 5 – 29 mL/min based on the Cockcroft-Gault equation). Hepatic Impairment Memantine hydrochloride should be administered with caution to patients with severe hepatic impairment [see Clinical Pharmacology (12.3)] .

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)

Most common adverse reactions (≥ 5 % and greater than placebo) are dizziness , headache, confusion and constipation. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Polygen Pharmaceuticals Inc. at 1-888-291-7337 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. See 17 for PATIENT COUNSELING INFORMATION and FDA-approved patient labeling. 6.1 Clinical Trials Experience Memantine hydrochloride was evaluated in eight double-blind placebo-controlled trials involving a total of 1862 dementia (Alzheimer’s disease, vascular dementia) patients (940 patients treated with memantine hydrochloride and 922 patients treated with placebo) for a treatment period up to 28 weeks. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a 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 Discontinuation In 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 a rate greater than placebo. Most Common Adverse Reactions In 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 1 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 a Higher Frequency than Placebo-treated Patients Adv e r se R eac t ion P l acebo (N = 922) % Me m a n t i ne hydrochloride (N = 940) % Body as a W ho le F a t i gue 1 2 P a in 1 3 C a rd iov a s c u l ar S y s t em H yp e r t e n s ion 2 4 C e n t r al a nd P e r ip h e r al N e rvo us S y s t em D i zz i n e ss 5 7 H ead ac he 3 6 G a s t ro i n t e s t i n al S y s t em Co n s t ip a t ion 3 5 Vo m i t i ng 2 3 M u s c u lo s k e l e t al S y s t em Back pain 2 3 Psychiatric Disorders Confusion 5 6 Somnolence 2 3 Hallucination 2 3 Respiratory System Coughing 3 4 Dyspnea 1 2 The overall profile of adverse reactions and the incidence rates for individual adverse reactions in the subpopulation of patients with moderate to severe Alzheimer’s disease were not different from the profile and incidence rates described above for the overall dementia population. Seizures Memantine hydrochloride has not been systematically evaluated in patients with a 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 a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a 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.

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 a 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 tablets, USP with other NMDA antagonists (amantadine, ketamine, and dextromethorphan) has not been systematically evaluated and such use should be approached with caution.