Drug interactions
Fosphenytoin + Roflumilast
Severity: Major
Fosphenytoin and Roflumilast: 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
Fosphenytoin is converted to phenytoin, which induces CYP3A4 and CYP1A2 and substantially reduces roflumilast exposure. Therapeutic effect may be lost.
What this interaction means in plain words
Fosphenytoin 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.
Fosphenytoin belongs to Central Nervous System; Roflumilast belongs to Respiratory.
Why it happens
Phenytoin induces CYP3A4 and CYP1A2, increasing roflumilast clearance.
What to do
Avoid the combination where possible, as the label advises against strong inducers. If both are required, monitor COPD control closely and consider an alternative to roflumilast.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fosphenytoin and Roflumilast, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Roflumilast
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Fosphenytoin with Roflumilast?
MediHelp rates the interaction as major. Fosphenytoin 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. Fosphenytoin is converted to phenytoin, which induces CYP3A4 and CYP1A2 and substantially reduces roflumilast exposure. Therapeutic effect may be lost.
How serious is the interaction between Fosphenytoin 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 where possible, as the label advises against strong inducers. If both are required, monitor COPD control closely and consider an alternative to roflumilast.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
