Contraception for Women Taking Enzyme-Inducing Antiepileptics

This transcript has been edited for clarity.

Topiramate, introduced as an antiepileptic drug (AED), is currently most widely used for prevention of migraine headaches.

Because reproductive-aged women represent a population in which migraines are prevalent, clinicians need guidance to help women taking topiramate make sound contraceptive choices.

Several issues are relevant here. First, women who have migraines with aura should avoid estrogen-containing contraceptive pills, patches, and rings. Instead, progestin-only methods, including the contraceptive implant, may be recommended to patients with migraines.

Second, because topiramate, as with a number of other AEDs, is a teratogen, women using this medication need highly effective contraception. This consideration may also lead clinicians to recommend use of the implant in women with migraines.

Finally, topiramate, along with other AEDs (phenytoin, carbamazepine, barbiturates, primidone, and oxcarbazepine) induces hepatic enzymes, which results in reduced serum contraceptive steroid levels.

Because there is uncertainty regarding the degree to which the use of topiramate reduces serum levels of etonogestrel (the progestin released by the implant), investigators performed a prospective study to assess the pharmacokinetic impact of topiramate in women with the implant.

Ongoing users of contraceptive implants who agreed to use additional nonhormonal contraception were recruited to a 6-week study, during which they took topiramate and periodically had blood drawn.