Memantine is best classified as what type of drug?

• A. NMDA receptor antagonist
• B. Cholinesterase inhibitor
• C. Dopamine reuptake inhibitor
• D. GABA agonist

Answer: (A)

Memantine is best classified as an NMDA receptor antagonist. It works as an uncompetitive, use-dependent blocker of NMDA receptors, meaning it only engages the channel when it’s open during glutamate activity. In Alzheimer's disease, excessive glutamate can cause excitotoxicity and neuronal injury. By dampening this excessive calcium influx through NMDA channels while largely sparing normal synaptic transmission, memantine helps reduce excitotoxic damage without indiscriminately slowing brain signaling. This mechanism is different from cholinesterase inhibitors, which raise acetylcholine to improve memory; it’s different from dopamine reuptake inhibitors, which alter dopaminergic signaling; and it’s different from GABA agonists, which amplify inhibitory GABAergic transmission. Clinically, memantine is used in moderate to severe Alzheimer's disease and can be combined with acetylcholinesterase inhibitors.