Memantine

Memantine is a medication used to treat moderate to severe Alzheimer's disease. It is less preferred than acetylcholinesterase inhibitors such as donepezil. Treatment should only be continued if beneficial effects are seen. It is taken by mouth. Memantine is a medication used to treat moderate to severe Alzheimer's disease. It is less preferred than acetylcholinesterase inhibitors such as donepezil. Treatment should only be continued if beneficial effects are seen. 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. A month supply in the United Kingdom costs the NHS about 1.60 GBP as of 2019. In the United States the wholesale cost of this amount is about US$5.50. In 2016 it was the 147th most prescribed medication in the United States with more than 4 million prescriptions. Memantine is used to treat moderate-to-severe Alzheimer's disease, especially for people who are intolerant of or have a contraindication to AChE (acetylcholinesterase) inhibitors. One guideline recommends memantine or a AChE inhibitor be considered in people in the early to mid stage of dementia. Memantine has been associated with a moderate improvement with only a small positive effect on cognition, mood, behavior, and the ability to perform daily activities in moderate to severe Alzheimer's disease. There does not appear to be any benefit in mild disease. While memantine can be used in combination with donepezil in those with dementia, the benefit of this is questionable and such dual use is not recommended by the National Institute of Clinical Excellence (NICE). Memantine when added to donepezil in those with moderate to severe dementia resulted in 'limited improvements' per a 2017 review. Effects in autism are unclear. Memantine is, in general, well-tolerated. Common adverse drug reactions (≥1% of people) include confusion, dizziness, drowsiness, headache, insomnia, agitation, and/or hallucinations. Less common adverse effects include vomiting, anxiety, hypertonia, cystitis, and increased libido. Like many other NMDA antagonists, memantine behaves as a dissociative anesthetic at supratherapeutic doses. Despite isolated reports, recreational use of memantine is rare due to the drug's long duration and limited availability. Also memantine seems to lack most of the psychoactive effects recreational users are usually looking for, such as euphoria or hallucinations. Memantine appears to be generally well-tolerated by children with autism spectrum disorder.