Memantine is a medication used to slow the progression of moderate-to-severe Alzheimers disease. It is taken by mouth.Common side effects include headache, constipation, sleepiness, and dizziness. Severe side effects may include blood clots, psychosis, and heart failure. It is believed to work by blocking NMDA receptors.Memantine was approved for medical use in the United States in 2003. It is available as a generic medication. In 2019, it was the 169th most commonly prescribed medication in the United States, with more than 3 million prescriptions. Medical use
Alzheimers disease and dementia
Memantine is used to treat moderate-to-severe Alzheimers disease, especially for people who are intolerant of or have a contraindication to AChE (acetylcholinesterase) inhibitors. One guideline recommends memantine or an AChE inhibitor be considered in people in the early-to-mid stage of dementia.Memantine has been associated with a modest improvement; with small positive effects on cognition, mood, behavior, and the ability to perform daily activities in moderate-to-severe Alzheimers disease. There does not appear to be any benefit in mild disease.Memantine when added to donepezil in those with moderate-to-severe dementia resulted in "limited improvements" in a 2017 review. The UK National Institute of Clinical Excellence (NICE) issued guidance in 2018 recommending consideration of the combination of memantine with donepezil in those with moderate-to-severe dementia. Psychiatry
Bipolar disorder
Memantine has been investigated as a possible augmentation strategy for depression in bipolar disorder but meta-analytic evidence does not support its clinical utility. Autism
Effects in autism are unclear. Adverse effects
Memantine is, in general, well tolerated.
Actavis appealed and in May a panel of the Second Circuit Court of Appeals upheld the injunction, and in June Actavis asked that its case be heard by the full Second Circuit panel. In August 2015, Actavis request was denied. Society and culture
Recreational use
One preclinical study on monkeys showed that memantine was capable of inducing a PCP-like intoxication. Because of its very long biological half-life, memantine was previously thought not to be recreational, although a few cases of sporadic recreational use have been described.A study examining self-reported use of memantine on the social network Reddit showed that the drug was used recreationally and as a nootropic, but also that it was misused in various illnesses as self-medication without strong scientific basis.