Drug interactions
Maraviroc + Phenytoin
Severity: Major
Maraviroc and Phenytoin: 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
Phenytoin induces CYP3A4 and may lower maraviroc concentrations, reducing antiviral efficacy. Maraviroc labeling advises a higher dose with strong inducers when not given with a strong CYP3A inhibitor. The legacy contraindication is not appropriate outside severe renal impairment.
What this interaction means in plain words
Maraviroc and Phenytoin 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.
Maraviroc belongs to Anti Virals; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and P-glycoprotein, increasing maraviroc clearance.
What to do
Increase maraviroc to 600 mg twice daily if no strong CYP3A inhibitor is coadministered, and monitor viral load. Avoid in patients with severe renal impairment.
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 Maraviroc and Phenytoin, 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 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
Other interactions of Maraviroc
- Amobarbital + Maraviroc Major
- Apalutamide + Maraviroc Major
- Carbamazepine + Maraviroc Major
- Clarithromycin + Maraviroc Major
- Efavirenz + Maraviroc Major
- Enzalutamide + Maraviroc Major
Frequently asked questions
Can I take Maraviroc with Phenytoin?
MediHelp rates the interaction as major. Maraviroc and Phenytoin 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 induces CYP3A4 and may lower maraviroc concentrations, reducing antiviral efficacy. Maraviroc labeling advises a higher dose with strong inducers when not given with a strong CYP3A inhibitor. The legacy contraindication is not appropriate outside severe renal impairment.
How serious is the interaction between Maraviroc and Phenytoin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Increase maraviroc to 600 mg twice daily if no strong CYP3A inhibitor is coadministered, and monitor viral load. Avoid in patients with severe renal impairment.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin 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.
