Memantine

Memantine is a prescription medication approved by the U.S. Food and Drug Administration to treat moderate-to-severe Alzheimer's disease. It is sold as a tablet, an extended-release capsule, and an oral solution, and is often prescribed together with a different class of Alzheimer's drug (cholinesterase inhibitors such as donepezil). Memantine does not cure Alzheimer's disease; it can help moderate symptoms and slow some of the decline associated with it. It is included in this library mainly for context: memantine acts on the same NMDA-receptor system as dissociative drugs like ketamine and PCP, but it is a legitimate, well-tolerated medicine with low potential for misuse, which makes it a useful point of comparison rather than a recreational substance.

Memantine is a low-affinity, uncompetitive NMDA-receptor antagonist. In Alzheimer's disease, excessive activity of the neurotransmitter glutamate at NMDA receptors is thought to contribute to ongoing nerve-cell damage. Memantine partially blocks these receptors in a way that dampens harmful overactivation while still allowing the normal signaling needed for memory and learning — a 'gentler' block than strong dissociatives produce. This is why memantine, despite sharing a receptor target with ketamine and PCP, does not produce the same intense dissociative state at therapeutic doses.

Taken as prescribed, memantine is generally well tolerated. The most common side effects include dizziness, headache, confusion, and constipation. Because it acts gradually and at controlled doses, it does not produce the euphoria or dissociative 'high' associated with recreational NMDA-blocking drugs, and it is not typically sought out for misuse. As with any medication, effects and tolerability vary between individuals, and it should be taken only as directed by a prescriber.

Memantine has a comparatively favorable safety profile when used as prescribed, and a low potential for abuse relative to other drugs in the dissociative family. Side effects are usually mild, but higher-than-prescribed doses or combination with other medicines can cause problems, and people with certain kidney conditions may need dose adjustments. As a prescription medication it should be taken only under medical supervision and not shared with others. If an overdose is suspected, contact Poison Control at 1-800-222-1222, or call 911 in an emergency. Anyone with questions about memantine should speak with their prescriber or pharmacist.