Co-prescription of antiepileptic drugs and contraceptives

Background: Enzyme-inducing antiepileptic drugs (AEDs) reduce the efficacy of oral contraceptives. Little is known of contraceptive practice among reproductive-age women who receive AEDs.

Study design: We explored the use of contraceptive methods among Dutch women aged 15 to 49 years with prescriptions of AEDs using pharmacy dispensing database. Drug dispensing data of AEDs and contraceptives in 2006 was retrieved from the InterAction Database (IADB.nl database). The prevalence of contraceptives use and distribution of different contraceptive methods were calculated.

Results: Of women who used enzyme-inducing AEDs in combination with any highly effective contraceptive method, over 40% were on an oral contraceptive (OC) containing <50 mcg estrogen. IUDs and injectable contraception were used in 22.5% of women receiving AEDs in combination with any highly effective contraceptive method, and 33.2% in those receiving enzyme-inducing AEDs in combination with any highly effective contraceptive method.

Conclusion: Fertile-age women who received AEDs often relied on less effective contraceptive methods. Prescribers should be more aware of the interaction between AEDs and OCs.