Pharmacology · single question
Carbamazepine (used for trigeminal neuralgia and epilepsy) has which mechanism of action?
Show answer and explanation
Correct answer: C. Sodium channel blocker — reduces high-frequency repetitive neuronal firing
- A. NMDA antagonism (ketamine, memantine) is yet another mechanism — not carbamazepine.
- B. GABA-A positive modulation (benzodiazepines, barbiturates) is a different anticonvulsant mechanism.
- C. Correct. Carbamazepine works by blocking voltage-gated sodium channels in their INACTIVE state, stabilizing hyperexcitable neuronal membranes and preventing repetitive high-frequency firing. This is also the mechanism of phenytoin and lamotrigine. For trigeminal neuralgia, it is the FIRST-LINE drug of choice.
- D. Potassium channel blockers would increase neuronal excitability — opposite of anticonvulsant action.