Antiepileptic medication and oral contraceptive interactions

Abstract

Hepatic enzyme-inducing antiepileptic drugs (AEDs) lower oral contraceptive (OC) sex hormone levels approximately 40% and increase the risk of unplanned pregnancies in women with epilepsy. AEDs also increase the risk of birth defects in offspring of women with epilepsy. We performed a national survey to determine obstetricians' and neurologists' knowledge of OC and AED interactions and the risk of birth defects for women with epilepsy taking AEDs. We received responses to a mailed questionnaire from 160 of 1,000 neurologists (16%) and 147 of 1,000 obstetricians (15%) from 47 states. Practice demographics and ages of responders were typical for U.S. neurologists and obstetricians. Ninety-one percent of neurologists and 75% of obstetricians said they treat women with epilepsy of child-bearing age. Only 4% of the neurologists and none of the obstetricians, however, knew the effects of the six most common AEDs on OCs, even though 27% of neurologists and 21% of obstetricians reported OC failures in their patients taking AEDs. Although increasing OC doses can compensate for insufficient OC sex hormone levels due to AEDs, most physicians do not increase the doses. Even though the risk of birth defects for the offspring of women with epilepsy is 4 to 6%, up from the background level of 2%, 44% of neurologists thought the risk was lower (0 to 3%), and some of the respondents guessed that it was as high as 50%. Many neurologists and obstetricians do not have accurate information to counsel women with epilepsy properly about their contraceptive and pregnancy choices.

The Effects of Epilepsy and Its Treatment on Sexual and Reproductive Function

“…Women with epilepsy are at risk for decreased reproductive function and unsuccessful pregnancy outcomes. Krauss reports that women have better access to the neurologist before pregnancy, less chance of interaction with a neurologist during pregnancy, and an insufficient and often erroneous body of educational advice given to them by obstetricians and neurologists (22). Considerable effort has been made in the past several years to disseminate information to consumers and professionals in order to improve women's health, fetal health, and successful deliveries of healthy neonates.…”

“…Nonenzyme-inducing drugs (felbamate, lamotrigine, VPA, gabapentin, and vigabatrin) do not interfere with birth control pills (Table 6). Unfortunately, this information is not well known by general neurologists and even less well known by obstetricians (22). Simply increasing the estrogenic component to 50 pg or more may prevent contraceptive failure.…”

Prevalencia de prescripción conjunta incorrecta de fármacos anticonvulsivantes y anticonceptivos hormonales Colombia, 2014

“…Estos hallazgos sugieren un conocimiento limitado por parte de los médicos de las interacciones entre la anticoncepción de tipo hormonal y los antiepilépticos, situación que se ha descrito en distintos estudios que evalúan los conocimientos que estos tienen de la epilepsia en la mujer, en especial cuando se valora minuciosamente dicha interacción (12,13). Este aspecto no fue evaluado en el presente estudio.…”

Co-prescription of antiepileptic drugs and contraceptives

“…An early survey in the US suggested that medical practitioners had limited knowledge of interactions between contraception and AEDs in women with epilepsy [8]. In another US study, only 4% of neurologists and none of the obstetricians knew the effects of the six most common AEDs on OCs [9]. A survey published in 2005 showed that about 70% of primary care physicians recognized that certain AEDs might interfere with the efficacy of OCs [10].…”