Rifabutin and Doravirine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Rifabutin
Doravirine
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
Reduced doravirine exposure, reduced efficacy and an increased risk of doravirine resistance
Interaction Deep Dive
Concomitant use of doravirine and rifabutin may result in reduced doravirine exposure, loss of doravirine efficacy, and development of resistance. Before initiating doravirine, it is recommended to wait at least 4 weeks after discontinuing rifabutin before starting doravirine. If concomitant use is necessary, increase the doravirine dosage to 100 mg twice daily1. If doravirine is coadministered with rifabutin, take one tablet of doravirine (IDVYNSO™) once daily as recommended, followed by one tablet of doravirine (PIFELTRO™) 100 mg approximately 12 hours after the dose of (IDVYNSO™) for the duration of rifabutin coadministration. In 15 subjects, coadministration of doravirine (100 mg single dose) and rifabutin (300 mg once daily) (100 mg BID resulted in similar pharmacokinetic values when compared to 100 mg QD without rifabutin) resulted in reduced AUC and Cmax of doravirine by 1.03-fold and 0.97-fold, respectively 2. In 12 healthy subjects, coadministration of doravirine (100 mg single dose) with rifabutin (300 mg once daily for 16 days) resulted in reduced AUC and C24 of doravirine by 50% and 68%, respectively 3.
Why it happens (mechanism)
Induction of CYP3A-mediated metabolism of doravirine
Literature reports
2 reports — tap to read
a) In 12 healthy subjects, coadministration of doravirine (100 mg single dose) with rifabutin (300 mg once daily for 16 days) resulted in reduced AUC and C24 of doravirine by 50% and 68%, respectively 3.
b) In 15 subjects, coadministration of doravirine (100 mg single dose) and rifabutin (300 mg once daily) (100 mg BID resulted in similar pharmacokinetic values when compared to 100 mg QD without rifabutin) resulted in reduced AUC and Cmax of doravirine by 1.03-fold and 0.97-fold, respectively 2.
Common questions
Can I take Rifabutin and Doravirine together?
Reduced doravirine exposure, reduced efficacy and an increased risk of doravirine resistance Always confirm with your pharmacist or prescriber before making any change.
How serious is the Rifabutin and Doravirine 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Rifabutin or Doravirine 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 (3)
- Product Information: PIFELTRO(TM) oral tablets, doravirine oral tablets. Merck Sharp & Dohme Corp (per FDA), Whitehouse Station, NJ, 2018. DailyMed
- Product Information: IDVYNSO™ oral tablet, doravirine and islatravir oral tablet. Merck Sharp & Dohme LLC, Rahway, NJ, 2026. DailyMed
- Product Information: MYCOBUTIN(R) oral capsules, rifabutin oral capsules. Pharmacia & Upjohn Co (per FDA), New York, NY, 2024. DailyMed
Keep reading about Rifabutin
Keep reading about Doravirine
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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