Levetiracetam's anticonvulsant mechanism is unique among antiepileptics. Which molecular target mediates its action?

• A SV2A (synaptic vesicle glycoprotein 2A) binding, modulating vesicle fusion and neurotransmitter release ✓
• B Voltage-gated sodium channel inactivation (similar to phenytoin)
• C Enhancement of GABA-A receptor chloride channel opening frequency
• D Inhibition of carbonic anhydrase reducing neuronal excitability

Explanation

Levetiracetam binds to SV2A, a synaptic vesicle glycoprotein expressed on presynaptic vesicles. SV2A modulates vesicle priming and fusion with the presynaptic membrane; levetiracetam binding selectively impairs repetitive firing in hyperexcitable neurons without affecting normal synaptic transmission significantly. This mechanism is distinct from sodium channel blockers (phenytoin, carbamazepine), GABA enhancers (benzodiazepines, barbiturates), and carbonic anhydrase inhibitors (topiramate, zonisamide).

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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