Buprenorphine and Letermovir: 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
Buprenorphine
Letermovir
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.
These two medicines can add up in a way worth watching. Letermovir (Prevymis) slows down a liver enzyme that normally breaks down buprenorphine. When that enzyme is blocked, more buprenorphine can build up in your body. That can mean stronger and longer opioid effects, like feeling very drowsy or, in more serious cases, slowed or shallow breathing.
The good news is this is very manageable. Your care team can tailor your buprenorphine dose and keep a closer eye on you, especially for extra sleepiness. Please don't change either medicine on your own. Just let your pharmacist or doctor know you take both, and call right away if you feel unusually sleepy or short of breath.
Mechanism: Letermovir is a moderate CYP3A4 inhibitor; buprenorphine is partly CYP3A4-metabolized. Inhibition reduces buprenorphine clearance, raising plasma exposure (increased AUC/Cmax) and prolonging opioid effect. Neither drug is a prodrug here, so the effect is enhanced, not reduced.
Direction: increased buprenorphine exposure and adverse-event risk (sedation, respiratory depression).
Evidence: probable. Onset: unspecified. Severity: major.
- If starting letermovir, consider reducing buprenorphine dose to stable effect; monitor sedation and respiration frequently.
- On discontinuing letermovir, anticipate need to increase buprenorphine dose; monitor for withdrawal.
- For subQ/long-acting 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
Because plasma buprenorphine levels rise when buprenorphine is taken alongside a CYP3A4 inhibitor, opioid effects such as respiratory depression may be prolonged. When a patient on buprenorphine requires a CYP3A4 inhibitor, it may be appropriate to lower the buprenorphine dose until drug effects stabilize, with frequent monitoring for sedation and respiratory depression. Conversely, if a CYP3A4 inhibitor is stopped in someone receiving buprenorphine, consider raising the buprenorphine dose until stable effects are reached while watching for opioid withdrawal signs2. Should dose adjustment prove impossible once the CYP3A4 inhibitor is gone, switch the patient back to a buprenorphine formulation that allows finer dose control. For patients transitioned from transmucosal buprenorphine that was given together with CYP3A4 inhibitors, verify that the plasma buprenorphine level achieved with subQ buprenorphine is sufficient. When a patient already receiving subQ buprenorphine needs a CYP3A4 inhibitor, watch for indications of over-medication. If buprenorphine toxicity or overdose signs and symptoms develop and the co-administered drug cannot be lowered or stopped, decrease the buprenorphine dose. If the available doses will not reach the target dose, stop the treatment and manage the patient with a buprenorphine formulation permitting more precise dose adjustments 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of buprenorphine
How to manage this interaction
Keep taking both as prescribed unless your care team tells you otherwise. Here is what teams typically do:
- Your buprenorphine dose may be adjusted and individualized by your care team, and they may monitor you more closely for sedation and slowed breathing.
- When letermovir is stopped later, your buprenorphine dose may need to go back up, with watching for withdrawal symptoms.
- If you use a long-acting or injectable form, your team may check that your dose is still right, or switch you to a form that allows finer adjustments.
Tell your pharmacist or prescriber you take both, and seek help promptly for unusual drowsiness or trouble breathing.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) The impact of concurrently administered CYP3A4 inhibitors on buprenorphine exposure in patients receiving subQ buprenorphine has not been examined; nevertheless, these interactions have been demonstrated in trials involving transmucosal buprenorphine. Buprenorphine's effects may vary according to the route of administration 1.
Common questions
Can I take Buprenorphine and Letermovir together?
Letermovir can raise buprenorphine levels and cause stronger, longer opioid effects, including slowed breathing. Don't change anything yourself; your care team can adjust the buprenorphine dose and monitor you closely. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Buprenorphine and Letermovir 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 Letermovir interaction managed?
Keep taking both as prescribed unless your care team tells you otherwise. Here is what teams typically do: Your buprenorphine dose may be adjusted and individualized by your care team, and they may monitor you more closely for sedation and slowed breathing. When letermovir is stopped later, your buprenorphine dose may need to go back up, with watching for withdrawal symptoms. If you use a long-act… 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 Letermovir 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 Buprenorphine
Keep reading about Letermovir
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