Lamotrigine exerts its antiepileptic effect primarily by:
- A Blocking voltage-gated sodium channels in their inactivated state ✓
- B Enhancing GABA-A receptor chloride conductance
- C Blocking NMDA glutamate receptors
- D Inhibiting carbonic anhydrase to reduce CSF production
Correct answer: A. Blocking voltage-gated sodium channels in their inactivated state
Explanation
Lamotrigine stabilises neuronal membranes by selectively binding to and prolonging the inactivated state of voltage-gated sodium channels, reducing repetitive high-frequency neuronal firing. It also has some activity on N- and P/Q-type calcium channels. GABA-A enhancement is the mechanism of benzodiazepines and barbiturates; NMDA blockade is seen with memantine; carbonic anhydrase inhibition is used by acetazolamide and topiramate.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.