Lamotrigine's primary mechanism of antiepileptic action is:
- A Blockade of voltage-gated sodium channels by binding preferentially to the inactivated state ✓
- B Enhancement of GABA-A receptor chloride conductance
- C Inhibition of GABA transaminase enzyme
- D Selective agonism at GABA-B receptors
Correct answer: A. Blockade of voltage-gated sodium channels by binding preferentially to the inactivated state
Explanation
Lamotrigine blocks voltage-gated sodium channels by preferentially binding to and stabilizing the inactivated state of the channel, preventing repetitive neuronal firing. It also inhibits release of glutamate and aspartate. This state-dependent sodium channel blockade is shared with phenytoin and carbamazepine. Vigabatrin inhibits GABA transaminase; valproate and benzodiazepines enhance GABA activity; baclofen is a GABA-B agonist.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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