Which factor would require increasing the emergency contraception dose when taking an enzyme-inducing anticonvulsant?

Which factor would require increasing the emergency contraception dose when taking an enzyme-inducing anticonvulsant?

• A. Age
• B. Severe asthma
• C. Epilepsy treated with phenobarbital
• D. Recent pregnancy test

Answer: (C)

Enzyme-inducing anticonvulsants speed up the body's drug metabolism, lowering the level of emergency contraception in the bloodstream and potentially reducing its effectiveness. Phenobarbital, used to treat epilepsy, is a strong inducer of hepatic enzymes such as CYPs and UGTs, so when it’s taken with emergency contraception the progestin is cleared more quickly. Because of that, a higher dose (or an alternative method) may be needed to achieve the same protective effect. The other factors don’t create this kind of pharmacokinetic interaction—age and severe asthma don’t by themselves change emergency contraception metabolism, and a recent pregnancy test doesn’t influence how the drug is processed.

Enzyme-inducing anticonvulsants speed up the body's drug metabolism, lowering the level of emergency contraception in the bloodstream and potentially reducing its effectiveness. Phenobarbital, used to treat epilepsy, is a strong inducer of hepatic enzymes such as CYPs and UGTs, so when it’s taken with emergency contraception the progestin is cleared more quickly. Because of that, a higher dose (or an alternative method) may be needed to achieve the same protective effect. The other factors don’t create this kind of pharmacokinetic interaction—age and severe asthma don’t by themselves change emergency contraception metabolism, and a recent pregnancy test doesn’t influence how the drug is processed.