Which neuro-drug acts as an antagonist at the NMDA receptor?

Memantine is a neuro-drug that functions as an antagonist at the NMDA (N-methyl-D-aspartate) receptor. NMDA receptors are a subtype of glutamate receptors that play a critical role in synaptic plasticity and memory function. In conditions such as Alzheimer's disease, excessive activation of NMDA receptors can lead to neurotoxicity due to the overabundance of glutamate, which may contribute to the progression of neuronal damage.

By acting as an antagonist, Memantine helps to regulate glutamate activity, preventing overstimulation of the NMDA receptors. This modulation can result in neuroprotective effects and alleviate some symptoms related to cognitive decline in Alzheimer's disease.

In contrast to Memantine, the other options listed—Rivastigmine, Donepezil, and Galantamine—are primarily cholinesterase inhibitors. They work by increasing the levels of acetylcholine in the brain, which is beneficial for improving cognitive function in Alzheimer's disease but do not act on the NMDA receptors. This distinction highlights why Memantine is the suitable choice for the mechanism of antagonism at NMDA receptors.