The hydrochloride salt of memantine, a low-affinity, voltage-dependent, noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. Memantine binds to and inhibits cation channels of glutamanergic NMDA receptors located in the central nervous system (CNS), preventing the prolonged influx of calcium ions and the associated neuronal excitotoxicity, and thereby potentially enhancing cognitive function. Memantine is also a 5-hydroxytryptamine type 3 (5HT3) receptor and nicotinic receptor antagonist. Check foractive clinical trials using this agent. or A drug used to treat dementia caused by Alzheimer disease. It is also being studied in the treatment of side effects from whole-brain radiation therapy for cancer and other conditions. Memantine hydrochloride blocks the uptake of calcium by certain brain cells and decreases their activity. It is a type of N-methyl-D-asparatate (NMDA) receptor antagonist. Also called Namenda.