PO (Adults): 5 mg once daily initially, increased at weekly intervals to 10 mg/day (5 mg twice daily), then 15 mg/day (5 mg once daily, 10 mg once daily as separate doses, then to target dose of 20 mg/day (as 10 mg twice daily).
It is postulated that memantine exerts its therapeutic effect as a low to moderate affinity uncompetitive nervous system N-methyl-D-aspartate (NMDA) receptor antagonist by binding preferentially to the NMDA receptor–operated cation channels.
Absorption: Well absorbed after oral administration.
Metabolism/Excretion: 57–82% excreted unchanged in urine by active tubular secretion moderated by pH dependent tubular reabsorption. Remainder metabolized; metabolites are not pharmacologically active.