Memantine-induced sustained unconsciousness

Abstract

Memantine, which is an N-methyl-d-aspartate receptor antagonist, is used for symptomatic treatment of moderate to severe Alzheimer's disease. Here, we present two cases of sustained unconsciousness after the use of memantine. Both cases developed consciousness disturbance after administration of memantine, and one showed myoclonus in the extremities. The elevated blood concentration of memantine might have been responsible for the unconsciousness in these cases. Ketamine, which is used as an anesthetic agent, is also a non-competitive N-methyl-d-aspartate receptor antagonist. It is possible that memantine exerts a sedative effect in a similar manner to ketamine. Care should be taken in use of memantine in elderly patients or in those with renal impairment.