Drug interactions
Etonogestrel + Primidone
Severity: Major
Etonogestrel and Primidone: major interaction.
Last updated Sources: US FDA label
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
Primidone is metabolised partly to phenobarbital and induces liver enzymes, lowering etonogestrel concentrations. This can result in contraceptive failure.
What this interaction means in plain words
Etonogestrel and Primidone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Etonogestrel belongs to Endocrine; Primidone belongs to Central Nervous System.
Why it happens
Primidone and its metabolite phenobarbital induce CYP3A4, increasing etonogestrel clearance.
What to do
Use a copper IUD or levonorgestrel IUD, or add a barrier method if etonogestrel is continued. Maintain backup contraception for several weeks after primidone is stopped.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Etonogestrel
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Etonogestrel with Primidone?
MediHelp rates the interaction as major. Etonogestrel and Primidone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Primidone is metabolised partly to phenobarbital and induces liver enzymes, lowering etonogestrel concentrations. This can result in contraceptive failure.
How serious is the interaction between Etonogestrel and Primidone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use a copper IUD or levonorgestrel IUD, or add a barrier method if etonogestrel is continued. Maintain backup contraception for several weeks after primidone is stopped.
What other medicines interact with Etonogestrel?
MediHelp also lists interactions of Etonogestrel with, for example, Amobarbital, Armodafinil, Bosentan. The full list is on the Etonogestrel page.
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