Encorafenib and Saquinavir: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Saquinavir
No brand names on recordEncorafenib
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 increased risk of QT interval prolongation, increased encorafenib exposure and an increased risk of encorafenib-related adverse events, reduced saquinavir exposure and reduced efficacy of saquinavir
Interaction Deep Dive
Both ritonavir-boosted saquinavir and encorafenib prolong the QT interval. The concomitant use of ritonavir-boosted saquinavir is contraindicated with drugs that are CYP3A4 substrates that can have life-threatening reactions with increased exposure, drugs that cause QT-interval prolongation, and with drugs that both increase saquinavir exposure and cause QT-interval prolongation. If concurrent use of ritonavir-boosted saquinavir and a QT-prolonging drug is required, perform a baseline ECG. Do not initiate coadministration if QT interval exceeds 450 msec. Perform an on-treatment ECG after 3 to 4 days of concurrent use; if the QT interval exceeds 480 msec or has increased more than 20 msec from baseline, discontinue one or both therapies2. Concomitant administration of encorafenib (CYP3A4 substrate) with a saquinavir (CYP3A4 inhibitors) may increase encorafenib exposure and may increase risk of encorafenib-related adverse reactions may also reduce saquinavir exposure and thus reduce efficacy of saquinavir. If coadministration cannot be avoided, reduce the encorafenib dose. If the current encorafenib dose is 450 mg/day, reduce to 150 mg/day and if it is 300, 225, or 150 mg/day, reduce to 75 mg/day 1.
Why it happens (mechanism)
Additive QT interval prolongation; inhibition of CYP3A4-mediated encorafenib metabolism; induction of CYP3A4 substrate metabolism by encorafenib
Literature reports
2 reports — tap to read
a) In a drug interaction study, coadministration of posaconazole (a strong CYP3A4 inhibitor) with encorafenib increased the AUC of encorafenib by 3-fold and increased the Cmax by 68% following a single dose of encorafenib 50 mg (0.1 times the usual dose) 1.
b) In a drug interaction study, repeat dose administration of encorafenib 450 mg once daily and binimetinib 45 mg twice daily with a single dose of midazolam 2 mg, a sensitive CYP3A4 substrate, decreased midazolam AUC by 82% and Cmax by 74% relative to midazolam 2 mg alone 1.
Common questions
Can I take Encorafenib and Saquinavir together?
An increased risk of QT interval prolongation, increased encorafenib exposure and an increased risk of encorafenib-related adverse events, reduced saquinavir exposure and reduced efficacy of saquinavir Always confirm with your pharmacist or prescriber before making any change.
How serious is the Encorafenib and Saquinavir interaction?
It is rated contraindicated. These should generally not be used together.
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 Encorafenib or Saquinavir 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 (2)
- Product Information: BRAFTOVI(R) oral capsules, encorafenib oral capsules. Array BioPharma Inc (per FDA), Boulder, CO, 2024. DailyMed
- Product Information: INVIRASE(R) oral capsules, oral tablets, saquinavir mesylate oral capsules, oral tablets. Genentech Inc (per FDA), South San Francisco, CA, 2019. DailyMed
Keep reading about Saquinavir
Keep reading about Encorafenib
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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