Does Thiotepa Interact with Rifampin?
Thiotepa and Rifampin have a major drug interaction according to U.S. FDA drug labeling data. Strong CYP3A4 inducer; avoid co-administration due to potential effects on efficacy and toxicity of thiotepa. The mechanism involves induction of cyp3a4-mediated metabolism of thiotepa to active metabolite tepa. 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
- Thiotepa Class
- Alkylating Drug
- Rifampin Class
- Rifamycin Antibacterial
- Management
- Close medical supervision required
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Thiotepa and Rifampin occurs because induction of cyp3a4-mediated metabolism of thiotepa to active metabolite tepa. Clinically, this means strong cyp3a4 inducer; avoid co-administration due to potential effects on efficacy and toxicity of thiotepa. This is classified as a major interaction, meaning it could cause serious harm if not properly managed. Your healthcare provider may need to adjust dosages, substitute one medication, or increase monitoring frequency.
What To Tell Your Doctor or Pharmacist
If you are taking Thiotepa and your doctor is considering prescribing Rifampin (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