AED Choice Requires an Individualized Approach
Generally, older AEDs are more likely to cause drug interactions, compared with newer drugs. Phenytoin, phenobarbital, and carbamazepine are enzyme inducers, which may cause problems for patients who are on statins. Valproic acid is a hepatic enzyme inhibitor, and phenytoin and valproic acid can have protein-binding interactions. Oral contraceptives reduce lamotrigine’s efficacy by doubling the clearance of the AED, Dr. French explained. “This can be problematic when women do not tell you when they are going on and off the contraceptive pill. They can have a breakthrough seizure, and it is only after the fact that you realize why that happened,” she said.
Interactions between oral contraceptive are common with other AEDs, as well. She cited a recent retrospective study involving 1,144 women with epilepsy ages 18 to 47 who provided demographic, epilepsy, AED, contraceptive, and pregnancy data. Survey results showed that 65% of their pregnancies were unintended. Oral forms of contraception had greater failure rates than nonoral forms, with intrauterine devices having the lowest failure rate.
—Adriene Marshall
Suggested Reading
Herzog AG, Mandle HB, Cahill KE, et al. Predictors of unintended pregnancy in women with epilepsy. Neurology. 2017;88(8):728-733.
Scheffer IE, Berkovic S, Capovilla G, et al. ILAE classification of the epilepsies: Position paper of the ILAE Commission for Classification and Terminology. Epilepsia. 2017;58(4):512-521.
