Clinicians should pay close attention to the hepatic enzyme induction properties of phenytoin and carbamazepine when prescribing to patients on oral contraceptives. Additionally, the use of isoniazid requires careful monitoring of AED serum levels due to its inhibitory effect on hepatic enzymes.

AEDs function via GABA-ergic enhancement, sodium channel blockade, T-type calcium channel inhibition, or NMDA antagonism.Barbiturates increase the duration of chloride channel opening, while benzodiazepines increase the frequency of opening.Enzyme-inducing AEDs (e.g., phenytoin, carbamazepine) can reduce oral contraceptive efficacy by five-fold.Isoniazid (INH) is a hepatic enzyme inhibitor that can dangerously elevate levels of fosphenytoin and carbamazepine.Ethosuximide is the primary treatment for absence seizures due to its action on T-type calcium channels.