Which of the following represent the mechanism of action of Memantine?
**Core Concept**
Memantine is a medication used in the treatment of Alzheimer's disease, acting as an N-methyl-D-aspartate (NMDA) receptor antagonist. It works by inhibiting the action of glutamate, the primary excitatory neurotransmitter in the brain.
**Why the Correct Answer is Right**
Memantine specifically binds to the NMDA receptor, blocking the action of glutamate and thereby preventing excessive neuronal excitation and damage. This is particularly relevant in Alzheimer's disease, where there is an overabundance of glutamate, leading to neuronal death. By blocking the NMDA receptor, memantine reduces the amount of glutamate that can bind and cause excitotoxicity.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect as memantine is not a cholinesterase inhibitor like donepezil, which increases the concentration of acetylcholine in the brain.
**Option B:** This is incorrect as memantine is not a monoamine oxidase inhibitor (MAOI) like selegiline, which increases the availability of dopamine, serotonin, and norepinephrine in the brain.
**Option C:** This is incorrect as memantine is not a selective serotonin reuptake inhibitor (SSRI) like fluoxetine, which increases the concentration of serotonin in the synaptic cleft.
**Clinical Pearl / High-Yield Fact**
Memantine is particularly useful in the treatment of Alzheimer's disease as it can be used in combination with cholinesterase inhibitors like donepezil, which can provide a synergistic effect and improve cognitive function.
**Correct Answer: C. N-methyl-D-aspartate (NMDA) receptor antagonist.**