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warnings and cautions
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) ] .
6 ADVERSE REACTIONS Most common adverse reactions (≥ 5 % and greater than placebo) are dizziness, headache, confusion and constipation. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Mylan Pharmaceuticals Inc. at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Memantine was evaluated in eight double-blind placebo-controlled trials involving a total of 1,862 dementia (Alzheimer’s disease, vascular dementia) patients (940 patients treated with memantine 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 up to 20 mg/day, the likelihood of discontinuation because of an adverse reaction was the same in the memantine 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-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 were dizziness, headache, confusion and constipation. Table 1 lists all adverse reactions that occurred in at least 2% of patients treated with memantine 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. Adverse Reaction Placebo (n = 922) % Memantine (n = 940) % Body as a Whole Fatigue 1 2 Pain 1 3 Cardiovascular System Hypertension 2 4 Central and Peripheral Nervous System Dizziness 5 7 Headache 3 6 Gastrointestinal System Constipation 3 5 Vomiting 2 3 Musculoskeletal System 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 has not been systematically evaluated in patients with a seizure disorder. In clinical trials of memantine, seizures occurred in 0.2% of patients treated with memantine 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.