Drug interactions
Medroxyprogesterone + Phenobarbital
Severity: Moderate
Medroxyprogesterone and Phenobarbital: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Phenobarbital induces hepatic enzymes and can lower circulating progestin concentrations. With medroxyprogesterone used for contraception or endometrial protection, this may reduce efficacy and lead to contraceptive failure or breakthrough bleeding.
What this interaction means in plain words
Medroxyprogesterone and Phenobarbital can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Induction of CYP3A4 and other hepatic enzymes by phenobarbital increases progestin metabolism.
What to do
Counsel on contraceptive reliability and consider a non-enzyme-inducing alternative or additional non-hormonal contraception. Watch for breakthrough bleeding or loss of the intended hormonal effect.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Medroxyprogesterone
Frequently asked questions
Can I take Medroxyprogesterone with Phenobarbital?
MediHelp rates the interaction as moderate. Medroxyprogesterone and Phenobarbital can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phenobarbital induces hepatic enzymes and can lower circulating progestin concentrations. With medroxyprogesterone used for contraception or endometrial protection, this may reduce efficacy and lead to contraceptive failure or breakthrough bleeding.
How serious is the interaction between Medroxyprogesterone and Phenobarbital?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Counsel on contraceptive reliability and consider a non-enzyme-inducing alternative or additional non-hormonal contraception. Watch for breakthrough bleeding or loss of the intended hormonal effect.
What other medicines interact with Medroxyprogesterone?
MediHelp also lists interactions of Medroxyprogesterone with, for example, Bosentan, Brigatinib, Eslicarbazepine. The full list is on the Medroxyprogesterone page.
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