Fosamprenavir and Avapritinib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fosamprenavir
Avapritinib
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
Increased avapritinib exposure and an increased risk of the incidence and severity of adverse reactions
Interaction Deep Dive
Coadministration of avapritinib 300 mg once daily with fluconazole 200 mg once daily (a moderate CYP3A inhibitor) is predicted to increase avapritinib AUC by 210% at steady state. Therefore, avoid concomitant administration of avapritinib with moderate CYP3A inhibitors. Coadministration may increase the incidence and severity of adverse reactions of avapritinib. If concomitant use cannot be avoided, reduce the starting dose of avapritinib or gastrointestinal stromal tumor (GIST): 100 mg orally once daily, for advanced systemic mastocytosis (AdvSM): 50 mg orally once daily and avoid concomitant use of a moderate CYP3A inhibitor for indolent systemic mastocytosis (ISM)1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated metabolism of avapritinib
Literature reports
1 report — tap to read
a) Coadministration of avapritinib 300 mg once daily with fluconazole 200 mg once daily (a moderate CYP3A inhibitor) is predicted to increase avapritinib AUC by 210% at steady state 1.
Common questions
Can I take Fosamprenavir and Avapritinib together?
Increased avapritinib exposure and an increased risk of the incidence and severity of adverse reactions Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fosamprenavir and Avapritinib interaction?
It is rated major. Potentially serious — often needs a change or close 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Fosamprenavir or Avapritinib 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 a safer alternative to one of these medications for me?
References (1)
- Product Information: AYVAKIT(TM) oral tablets, avapritinib oral tablets. Blueprint Medicines Corporation (per manufacturer), Cambridge, MA, 2024. DailyMed
Keep reading about Fosamprenavir
Keep reading about Avapritinib
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.
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