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 drugs long duration and limited availability. Also memantine seems to lack effects such as euphoria or hallucinations.Memantine appears to be generally well tolerated by children with autism spectrum disorder. Pharmacology
Glutamate
A dysfunction of glutamatergic neurotransmission, manifested as neuronal excitotoxicity, is hypothesized to be involved in the etiology of Alzheimers disease. Targeting the glutamatergic system, specifically NMDA receptors, offers a novel approach to treatment in view of the limited efficacy of existing drugs targeting the cholinergic system.Memantine is a low-affinity voltage-dependent uncompetitive antagonist at glutamatergic NMDA receptors. By binding to the NMDA receptor with a higher affinity than Mg2+ ions, memantine is able to inhibit the prolonged influx of Ca2+ ions, particularly from extrasynaptic receptors, which forms the basis of neuronal excitotoxicity. The low affinity, uncompetitive nature, and rapid off-rate kinetics of memantine at the level of the NMDA receptor-channel, however, preserves the function of the receptor at synapses, as it can still be activated by physiological release of glutamate following depolarization of the postsynaptic neuron. The interaction of memantine with NMDA receptors plays a major role in the symptomatic improvement that the drug produces in Alzheimers disease.
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.