Pharmacology Guide for Brain Injury Treatment: Memory and CognitionTo download and print the newsletter, you need Adobe's free reader installed on your computer. Receptor antagonist. Memantine is believed to function as a low to moderate affinity uncompetitive (open-channel) NMDA receptor antagonist which binds to the NMDA receptor-operated cation channels. The clearance of memantine was reduced by about 80% under alkaline urine conditions at pH 8. Therefore, alterations of urine pH towards the alkaline state may lead to an accumulation of the drug with a possible increase in adverse effects. Drugs that alkalinize the urine (e.g. carbonic anhydrase inhibitors, sodium bicarbonate) would be expected to reduce renal elimination of memantine.