Does Phenobarbital Sodium Interact with Cyp3a Inducers?
Phenobarbital Sodium and Cyp3a Inducers have a moderate drug interaction according to U.S. FDA drug labeling data. Inducers may decrease phenobarbital exposure, reducing efficacy and increasing risk of breakthrough seizures. Closely monitor and consider dosage adjustment. The mechanism involves phenobarbital is a substrate of cyp2c9, cyp2c19, cyp2e1, and ugts; induction increases metabolism. 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
- Moderate
- Management
- Monitor for effects
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Phenobarbital Sodium and Cyp3a Inducers occurs because phenobarbital is a substrate of cyp2c9, cyp2c19, cyp2e1, and ugts; induction increases metabolism. Clinically, this means inducers may decrease phenobarbital exposure, reducing efficacy and increasing risk of breakthrough seizures. closely monitor and consider dosage adjustment. This is classified as a moderate interaction. While it may not require stopping either medication, your healthcare provider should be aware you are taking both so they can monitor for potential effects and adjust treatment if necessary.
What To Tell Your Doctor or Pharmacist
If you are taking Phenobarbital Sodium and your doctor is considering prescribing Cyp3a Inducers (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 whether any dosage adjustments are needed
- Never stop or change either medication without first consulting your healthcare provider