Which of the following statements about anti-epileptics is false?: (A) Phenytoin and carbamazepine act by prolonging the inactivated state of Na+ channels, (B) Carbamazepine can be used in trigeminal neuralgias, (C) Diazepam is an anticonvulsant drug, (D) Lamotrigine mainly acts by causing GABA mediated Cl- channel opening
Answer is D. prolongation of Na+ channel inactivation and suppression of high frequency firing has been demonstrated. In addition, it may directly block voltage sensitive Na+ channels, thus stabilizing the presynaptic membrane and preventing release of excitatory neurotransmitters, mainly glutamate and aspaate. Ref KD Tripati 8thh ed.