Aprepitant and Buprenorphine: 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
Aprepitant
Buprenorphine
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.
Here's what's going on. Aprepitant (Emend) slows down a liver enzyme called CYP3A4, which is one of the ways your body breaks down buprenorphine. When that breakdown slows, more buprenorphine can build up in your blood. That can make its effects stronger and last longer, including drowsiness and slowed breathing.
This is a well-recognized combination, and your care team can manage it safely. The good news is that your doctor may lower your buprenorphine dose while you are on aprepitant and watch you a bit more closely. Please don't change anything on your own, just talk with your pharmacist or prescriber so they can tailor your plan.
Mechanism: Aprepitant is a moderate CYP3A4 inhibitor; buprenorphine is a CYP3A4 substrate. Inhibition reduces buprenorphine metabolism, increasing its plasma concentration and exposure (neither agent's active-form activation is at issue here).
Effect / direction: Increased buprenorphine exposure, raising risk of prolonged opioid effects including sedation and respiratory depression. Severity major, evidence probable, onset unspecified.
Management:
- Consider reducing buprenorphine dose until stable, monitor frequently for sedation and respiratory depression.
- On discontinuing aprepitant, consider a dose increase and monitor for withdrawal.
- For subQ formulations, monitor for over-medication; transition to a titratable formulation if precise adjustment is needed.
What happens
Increased buprenorphine exposure and an increased risk of buprenorphine-related adverse events
Interaction Deep Dive
Coadministering buprenorphine with a CYP3A4 inhibitor can raise buprenorphine plasma levels, which may lead to extended opioid effects such as respiratory depression. When a patient on buprenorphine requires a CYP3A4 inhibitor, it may be appropriate to lower the buprenorphine dose until drug effects stabilize, with frequent observation for sedation and respiratory depression. Conversely, if a CYP3A4 inhibitor is stopped in a patient being treated with buprenorphine, an increase in the buprenorphine dose may be warranted until stable drug effects are reached, along with monitoring for indications of opioid withdrawal2. Should dose adjustment prove impossible once the CYP3A4 inhibitor is gone, switch the patient back to a buprenorphine formulation that allows finer dose titration. For patients transitioned from transmucosal buprenorphine given together with CYP3A4 inhibitors, confirm through monitoring that subQ buprenorphine delivers an adequate plasma buprenorphine level. For those already receiving subQ buprenorphine who then need a CYP3A4 inhibitor, watch for indications of over-medication. If buprenorphine toxicity or overdose symptoms develop and the accompanying medication cannot be lowered or stopped, decrease the buprenorphine dose. When the available doses do not allow the target dose to be reached, halt treatment and manage the patient using a buprenorphine formulation that supports 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 the right adjustments.
- Your team may lower your buprenorphine dose while you are on aprepitant, and adjust it back up when aprepitant is stopped.
- They may monitor you more closely for sedation and slowed or shallow breathing.
- If you are on a long-acting injectable form, your team may check that your dose is still right.
Get help right away if you feel very drowsy, confused, or notice slow or shallow breathing. Ask your pharmacist or prescriber before changing anything.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) Studies have not evaluated how CYP3A4 inhibitors given concurrently affect buprenorphine exposure in individuals receiving subQ buprenorphine; nevertheless, these interactions have been demonstrated in investigations involving transmucosal buprenorphine. Buprenorphine's effects may vary according to the route by which it is administered 1.
Common questions
Can I take Aprepitant and Buprenorphine together?
Aprepitant can raise buprenorphine levels and increase sedation and breathing risks, so your care team may lower your buprenorphine dose and watch you closely. Keep both as prescribed and check with your pharmacist or doctor before any changes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Aprepitant and Buprenorphine 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 Aprepitant and Buprenorphine interaction managed?
Keep taking both medicines as prescribed unless your care team tells you otherwise. This combination can be managed with the right adjustments. Your team may lower your buprenorphine dose while you are on aprepitant, and adjust it back up when aprepitant is stopped. They may monitor you more closely for sedation and slowed or shallow breathing. If you are on a long-acting injectable form, your tea… 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 Aprepitant or Buprenorphine 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 Aprepitant
Keep reading about Buprenorphine
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