Several compounds act as NMDA receptor antagonists, with some of the most well-known being ketamine, phencyclidine (PCP), dextromethorphan, and memantine. While ketamine and PCP are often associated with their recreational use and potential for abuse, memantine is primarily used in clinical settings for treating Alzheimer's disease. Dextromethorphan, found in cough syrups, is also recognized for its potential misuse.
