Drug interactions
Phenobarbital + Pirfenidone
Severity: Major
Phenobarbital and Pirfenidone: major 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 drug-metabolizing enzymes and may lower pirfenidone exposure, reducing its antifibrotic efficacy. The effect is predicted from pirfenidone's CYP1A2 metabolism.
What this interaction means in plain words
Phenobarbital and Pirfenidone 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.
Why it happens
Enzyme induction, including CYP1A2, increases pirfenidone clearance.
What to do
Avoid the combination if possible and consider an alternative anticonvulsant; if it is unavoidable, monitor clinical response and lung function.
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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Other interactions of Pirfenidone
Frequently asked questions
Can I take Phenobarbital with Pirfenidone?
MediHelp rates the interaction as major. Phenobarbital and Pirfenidone 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. Phenobarbital induces drug-metabolizing enzymes and may lower pirfenidone exposure, reducing its antifibrotic efficacy. The effect is predicted from pirfenidone's CYP1A2 metabolism.
How serious is the interaction between Phenobarbital and Pirfenidone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible and consider an alternative anticonvulsant; if it is unavoidable, monitor clinical response and lung function.
What other medicines interact with Pirfenidone?
MediHelp also lists interactions of Pirfenidone with, for example, Carbamazepine, Ciprofloxacin, Fluvoxamine. The full list is on the Pirfenidone page.
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