Does Tacrolimus Interact with Letermovir?
Tacrolimus and Letermovir have a major drug interaction according to U.S. FDA drug labeling data. Increase tacrolimus dose and monitor tacrolimus whole blood trough concentrations [see Dosage and Administration ( 2.2 , 2.6 ) and Clinical Pharmacology (12.3 ) ] Strong CYP3A Inhibitors : Protease inhibitors (e.g, nelfinavir, telaprevir, boceprevir, ritonavir), azole antifungals (e.g., voriconazole, posaconazole, itraconazole, ketoconazole), antibiotics (e.g., clarithromycin, troleandomycin, chloramphenicol), nefazodone,letermovir, Schisandra sphenanthera extracts May increase tacrolimus whole blood trough concentrations and increase the risk of serious adverse reactions (e.g., neurotoxicity, QT prolongation).A rapid, sharp rise in tacrolimus levels may occur early, despite an immediate reduction of tacrolimus dose [see Warnings and Precautions ( 5.6 , 5.11 , 5.12 )] Reduce tacrolimus dose (for voriconazole and posaconazole, give one-third of the original dose) and adjust dose based on tacrolimus whole blood trough concentrations [see Dosage and Administration ( 2.2 , 2.6 ) and Clinical Phamacology ( 12.3 )]. Patients taking both medications should consult their healthcare provider before starting, stopping, or changing the dosage of either drug. This information is based on official FDA drug labeling sourced from OpenFDA and the NIH National Library of Medicine.
- Severity
- Major
- Tacrolimus Class
- Calcineurin Inhibitor Immunosuppressant
- Letermovir Class
- Cytomegalovirus DNA Terminase Complex Inhibitor
- Management
- Close medical supervision required
- Data Source
- U.S. FDA via OpenFDA
What To Tell Your Doctor or Pharmacist
If you are taking Tacrolimus and your doctor is considering prescribing Letermovir (or vice versa), make sure to:
- Inform your doctor and pharmacist of all current medications, including over-the-counter drugs and supplements
- Ask whether the benefits of combining these medications outweigh the risks for your specific situation
- Ask what symptoms to watch for that would indicate the interaction is causing problems
- Ask how frequently you should be monitored while these are co-prescribed
- Ask whether any dosage adjustments are needed
- Never stop or change either medication without first consulting your healthcare provider