This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Drugs which potentiate effect of NMDA at NMDA receptors are all except ? 
Select and explain. 
A. Ketamine, B. Aspaic acid, C. D alanine, D. Homocysteic acid
A: Ketamine
Answer: A: Ketamine 
Explanation: Ans. is 'a' i.e., Ketamine Ketamine is NMDA receptor blocker so it does not potentiate the NMDA action.