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Clinical Trials Experience
NAMENDA 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 NAMENDA 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 NAMENDA up to 20 mg/day, the likelihood of discontinuation because of an adverse reaction was the same in the NAMENDA 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 NAMENDA-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 NAMENDA were dizziness, headache, confusion and constipation. Table 1 lists all adverse reactions that occurred in at least 2% of patients treated with NAMENDA and at an incidence greater than placebo.
Table 1: Adverse Reactions Reported in Controlled
Clinical Trials in at Least 2% of Patients Receiving NAMENDA and at a Higher
Frequency than Placebo-treated Patients
(N = 922) %
(N = 940) %
|Body as a Whole|
|Central and Peripheral Nervous System|
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.
NAMENDA has not been systematically evaluated in patients with a seizure disorder. In clinical trials of NAMENDA, seizures occurred in 0.2% of patients treated with NAMENDA and 0.5% of patients treated with placebo.
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:
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.
Read the Namenda (memantine hcl) Side Effects Center for a complete guide to possible side effects
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.
Use With Other N-methyl-D-aspartate (NMDA) Antagonists
The combined use of NAMENDA with other NMDA antagonists (amantadine, ketamine, and dextromethorphan) has not been systematically evaluated and such use should be approached with caution.
Read the Namenda Drug Interactions Center for a complete guide to possible interactions
Last reviewed on RxList: 9/25/2014
This monograph has been modified to include the generic and brand name in many instances.
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