Buprenorphine and Amprenavir: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amprenavir
No brand names on recordBuprenorphine
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.
You've been prescribed amprenavir (an HIV medicine) along with buprenorphine (used for pain or for treating opioid dependence). Here's what matters: amprenavir slows down a liver enzyme (called CYP3A4) that normally breaks down buprenorphine. When that enzyme is blocked, buprenorphine can build up in your body.
Higher levels can mean stronger and longer opioid effects, like heavy drowsiness or slowed breathing. That's why this pairing is taken seriously. The good news is your care team can manage this by adjusting your buprenorphine dose and watching you more closely. Please don't stop or change either medicine on your own, just talk with your doctor or pharmacist.
Effect: Amprenavir (a CYP3A4 inhibitor) reduces buprenorphine metabolism, increasing buprenorphine plasma exposure and the risk of prolonged opioid effects, including sedation and respiratory depression. Buprenorphine is the affected object drug (not a prodrug), so inhibition increases its effect.
- Mechanism: inhibition of CYP3A4-mediated buprenorphine metabolism
- Severity/evidence: major; probable
- Management: if initiating amprenavir, consider reducing buprenorphine dose to stable effect and monitor frequently for sedation/respiratory depression. On discontinuing the inhibitor, consider a buprenorphine dose increase and monitor for withdrawal.
- For subQ formulations, monitor for over-medication; use a formulation allowing precise titration if needed.
What happens
Increased buprenorphine exposure and an increased risk of buprenorphine-related adverse events
Interaction Deep Dive
Combining buprenorphine with a CYP3A4 inhibitor can raise buprenorphine plasma levels, which may lead to extended opioid effects such as respiratory depression. When a CYP3A4 inhibitor must be given to a patient already taking buprenorphine, consider lowering the buprenorphine dose until stable drug effects are reached, and check frequently for sedation and respiratory depression. Conversely, when a CYP3A4 inhibitor is stopped in a patient on buprenorphine, consider raising the buprenorphine dose until stable drug effects are reached, and watch for indications of opioid withdrawal2. If dose adjustment is not possible once the CYP3A4 inhibitor is gone, move the patient back to a buprenorphine formulation that allows finer dose titration. For patients switched from transmucosal buprenorphine taken together with CYP3A4 inhibitors, verify that the plasma buprenorphine level delivered by subQ buprenorphine is sufficient. For patients already receiving subQ buprenorphine who need to start a CYP3A4 inhibitor, monitor for signs and symptoms of over-medication. Should signs and symptoms of buprenorphine toxicity or overdose develop while the concomitant drug cannot be lowered or stopped, decrease the buprenorphine dose. When the available doses do not allow the target dose to be reached, stop treatment and manage the patient with a buprenorphine formulation that permits more precise dose adjustments 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of buprenorphine
How to manage this interaction
Keep taking both medicines as prescribed unless your care team tells you otherwise. This combination can be managed with dose tailoring and closer monitoring.
- Your team may reduce your buprenorphine dose while you are on amprenavir, then adjust it again if amprenavir is stopped.
- Expect closer monitoring for sedation and slowed breathing, and for withdrawal signs when the inhibitor is stopped.
- If you use a long-acting (injectable) buprenorphine, your team may switch to a form that allows finer dose adjustments.
- Call your doctor or pharmacist if you feel unusually drowsy, foggy, or notice slow or shallow breathing.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) Studies have not examined how concurrently administered CYP3A4 inhibitors influence buprenorphine exposure in individuals receiving subQ buprenorphine; nevertheless, these interactions have been documented in studies that used transmucosal buprenorphine. Buprenorphine's effects may vary according to the route of administration 1.
Common questions
Can I take Buprenorphine and Amprenavir together?
Amprenavir can raise buprenorphine levels and prolong opioid effects like drowsiness and slowed breathing, so your care team may lower your buprenorphine dose and monitor you more closely. Do not adjust either medicine yourself. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Buprenorphine and Amprenavir 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 is the Buprenorphine and Amprenavir interaction managed?
Keep taking both medicines as prescribed unless your care team tells you otherwise. This combination can be managed with dose tailoring and closer monitoring. Your team may reduce your buprenorphine dose while you are on amprenavir, then adjust it again if amprenavir is stopped. Expect closer monitoring for sedation and slowed breathing, and for withdrawal signs when the inhibitor is stopped. If y… Management is individual — always follow your own care team's guidance.
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 Buprenorphine or Amprenavir 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: BRIXADI(TM) subcutaneous extended-release injection, buprenorphine subcutaneous extended-release injection. Braeburn Inc (per FDA), Plymouth Meeting, PA, 2023. DailyMed
- Product Information: ZUBSOLV(R) sublingual tablets, buprenorphine naloxone sublingual tablets. Orexo US Inc (per FDA), Morristown, NJ, 2023. DailyMed
Keep reading about Amprenavir
Keep reading about Buprenorphine
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