Drug interactions
Fostemsavir + Methotrexate
Severity: Moderate
Fostemsavir and Methotrexate: moderate 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
Fostemsavir's active metabolite inhibits OATP1B1/3 and BCRP, which are involved in methotrexate transport. Methotrexate exposure may increase, with greater risk of toxicity.
What this interaction means in plain words
Fostemsavir and Methotrexate can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fostemsavir belongs to Anti Virals; Methotrexate belongs to Oncology.
Why it happens
Inhibition of OATP1B1/3 and BCRP may reduce methotrexate uptake and efflux.
What to do
Monitor blood counts and renal and hepatic function. Reduce the methotrexate dose if toxicity develops.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fostemsavir and Methotrexate, 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 7 days on the web. No card needed.
Other interactions of Methotrexate
- Acitretin + Methotrexate Contraindicated
- Adenovirus types 4 and 7 live + Methotrexate Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Methotrexate Contraindicated
- Ketorolac + Methotrexate Contraindicated
- Measles mumps and rubella vaccine live + Methotrexate Contraindicated
- Measles mumps and rubella vaccine + Methotrexate Contraindicated
Other interactions of Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Fostemsavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Fostemsavir with Methotrexate?
MediHelp rates the interaction as moderate. Fostemsavir and Methotrexate can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Fostemsavir's active metabolite inhibits OATP1B1/3 and BCRP, which are involved in methotrexate transport. Methotrexate exposure may increase, with greater risk of toxicity.
How serious is the interaction between Fostemsavir and Methotrexate?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood counts and renal and hepatic function. Reduce the methotrexate dose if toxicity develops.
What other medicines interact with Methotrexate?
MediHelp also lists interactions of Methotrexate with, for example, Acitretin, Adenovirus types 4 and 7 live, Influenza virus vaccine quadrivalent intranasal. The full list is on the Methotrexate 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.
