Table 7. Antiepileptic drugs and their effect on enzyme induction and contraceptive reliability.

Enzyme induction	Drugs	Contraceptive reliability
Marked	barbiturates, carbamazepine, felbamate, oxcarbazepine, phenytoin, primidone, clonazepam, topiramate	not reliable
Reciprocal interaction	lamotrigine (dose must be raised; EE induces metabolism of lamotrigine and lamotrigine induces metabolism of LNG)	beware of possible effect
None	valproic acid, gabapentin, levetiracetam, tiagabine, vigabatrin, zonisamide, pregabalin	fully reliable

EE, ethinyl estradiol; LNG, levornogestrel; LTG, lamotrigine