CONTRACEPTIVE drug interactions were common among people with epilepsy of childbearing potential prescribed hormonal contraception and enzyme-inducing antiseizure medications, according to a retrospective study of US Medicaid beneficiaries. Published in data covering 2016–2021, the findings highlighted potential gaps in the safe prescribing of contraception and antiseizure medication combinations.
The study analysed Medicaid claims data for female beneficiaries with epilepsy who received antiseizure medications (ASMs) and were prescribed at least one hormonal contraceptive method susceptible to hepatic enzyme induction. Researchers assessed prescription and procedure dates to identify overlapping use lasting at least 14 days.
The overall cohort included 110,976 people with epilepsy of childbearing potential, with a median age of 24 years. Of these, 21,923 were prescribed a susceptible contraceptive method between 2018 and 2021.
Among this group, 7,154 individuals, equivalent to 32.6%, experienced at least 14 days of overlapping prescriptions for a susceptible hormonal contraceptive and an enzyme-inducing ASM. The median duration of overlap was 218 days, with an interquartile range of 74–511 days.
These findings indicated that potentially interacting prescriptions affected a substantial proportion of the population receiving susceptible hormonal contraception.
The researchers used regression analyses to investigate characteristics associated with overlapping prescriptions and longer periods of overlap. Intellectual disability was associated with both outcomes, with an adjusted odds ratio (aOR) of 2.33 (95% confidence interval [CI]: 2.19–2.48) for any overlap and an estimate of 2.27 (95% CI: 2.05–2.53) for longer overlap.
Drug-resistant epilepsy was also associated with increased likelihood of overlap (aOR: 1.73; 95% CI: 1.62–1.84) and longer overlap (estimate: 1.27; 95% CI: 1.14–1.41).
Age was another associated characteristic. Compared with individuals aged 19–34 years, those older than 35 years had higher odds of experiencing any overlap (aOR: 1.45; 95% CI: 1.32–1.59) and were more likely to have a greater proportion of overlapping days (estimate: 1.51; 95% CI: 1.29–1.75).
The findings highlighted the importance of considering potential interactions when prescribing hormonal contraception to people with epilepsy. Enzyme-inducing ASMs can reduce the effectiveness of susceptible hormonal methods, potentially compromising contraceptive protection.
The authors noted several limitations. The claims data did not capture medication adherence, contraceptive counselling, pregnancy intentions, sexual orientation, sexual activity or barrier contraceptive use. Consequently, the observed overlap did not establish whether individuals experienced reduced contraceptive effectiveness or unintended pregnancy.
The results nevertheless identified populations in whom interacting prescriptions were more common. Reviewing ASM and contraceptive combinations may therefore be an important consideration when supporting contraceptive choices for people with epilepsy.
Reference
Harrison E et al. Contraceptive and enzyme-inducing antiseizure medication coprescription among US Medicaid beneficiaries with epilepsy. Neurology. 2026;107(9): e218679.
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