Which drug is a NMDA receptor antagonist used in dementia care?

• A. Memantine
• B. Donepezil
• C. Rivastigmine
• D. Galantamine

Answer: (A)

Memantine is the NMDA receptor antagonist used in dementia care. It works by blocking NMDA receptors activated by glutamate, which helps prevent calcium overload and excitotoxic neuronal injury that is implicated in Alzheimer's disease. This mechanism addresses a different aspect of dementia pathology than the cholinergic system targeted by the other drugs listed, which are acetylcholinesterase inhibitors that boost acetylcholine to improve memory and cognition in milder to moderate stages. Memantine is approved for moderate to severe Alzheimer's disease and can be used alone or in combination with acetylcholinesterase inhibitors. It is generally well tolerated, with possible side effects like dizziness, confusion, or constipation, and dosing is adjusted for renal function.