Levetiracetam's mechanism of action in epilepsy is distinct from all other antiepileptics because it:
- A Binds synaptic vesicle glycoprotein 2A (SV2A), modulating synaptic vesicle exocytosis and reducing neurotransmitter release during high-frequency firing ✓
- B Blocks voltage-gated Na+ channels in the inactivated state, stabilising neuronal membranes
- C Enhances GABA-A receptor chloride current by allosterically potentiating GABA binding
- D Blocks AMPA glutamate receptors, reducing excitatory post-synaptic potentials
Correct answer: A. Binds synaptic vesicle glycoprotein 2A (SV2A), modulating synaptic vesicle exocytosis and reducing neurotransmitter release during high-frequency firing
Explanation
Levetiracetam binds synaptic vesicle protein 2A (SV2A), a ubiquitous transmembrane protein in synaptic vesicles. By modulating SV2A, it selectively reduces neurotransmitter release during high-frequency (pathological) firing without affecting normal transmission. This unique pre-synaptic mechanism is completely distinct from Na+ channel blockade (phenytoin, carbamazepine), GABA enhancement (benzodiazepines, barbiturates), or glutamate antagonism. It has no significant drug interactions as it is not CYP-metabolised.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.