Fosamprenavir and Nimodipine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fosamprenavir
Nimodipine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increase in plasma concentrations of nimodipine
Interaction Deep Dive
Use of fosamprenavir, a CYP3A4 inhibitor2, together with nimodipine, a CYP3A4 substrate, may result in increased nimodipine plasma concentrations and an increased risk of nimodipine related side effects. Increased blood pressure monitoring and dose reduction of nimodipine may be warranted during coadministration 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated nimodipine metabolism by amprenavir, the active metabolite of fosamprenavir
Common questions
Can I take Fosamprenavir and Nimodipine together?
An increase in plasma concentrations of nimodipine Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fosamprenavir and Nimodipine interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Fosamprenavir or Nimodipine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Product Information: nimodipine oral capsules, nimodipine oral capsules. Caraco Pharmaceutical Laboratories, Ltd. (per DailyMed), Detroit, MI, 2012. DailyMed
- Product Information: LEXIVA(R) oral tablets, suspension, fosamprenavir calcium oral tablets, suspension. ViiV Healthcare and Vertex Pharmaceuticals Incorporated (per manufacturer), Research Triangle Park, NC, 2011. DailyMed
Keep reading about Fosamprenavir
Keep reading about Nimodipine
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist