Drug interactions
Phenytoin + Roflumilast
Severity: Major
Phenytoin and Roflumilast: 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
Phenytoin is a strong inducer of CYP enzymes and can substantially lower roflumilast and active metabolite exposure. Roflumilast labeling advises against use with strong inducers because efficacy may be lost.
What this interaction means in plain words
Phenytoin and Roflumilast 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.
Phenytoin belongs to Central Nervous System; Roflumilast belongs to Respiratory.
Why it happens
Induction of CYP3A4 and CYP1A2 by phenytoin increases roflumilast metabolism.
What to do
Avoid the combination and consider an alternative COPD therapy. If both are continued, monitor exacerbation frequency closely.
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
- Roflumilast - FDA drug label (DailyMed) — openFDA / DailyMed
Other interactions of Roflumilast
Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Phenytoin with Roflumilast?
MediHelp rates the interaction as major. Phenytoin and Roflumilast 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. Phenytoin is a strong inducer of CYP enzymes and can substantially lower roflumilast and active metabolite exposure. Roflumilast labeling advises against use with strong inducers because efficacy may be lost.
How serious is the interaction between Phenytoin and Roflumilast?
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 and consider an alternative COPD therapy. If both are continued, monitor exacerbation frequency closely.
What other medicines interact with Roflumilast?
MediHelp also lists interactions of Roflumilast with, for example, Apalutamide, Carbamazepine, Efavirenz. The full list is on the Roflumilast page.
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