Does Felbamate Interact with Carbamazepine?
Felbamate and Carbamazepine have a major drug interaction according to U.S. FDA drug labeling data. Felbamate decreases steady-state carbamazepine plasma concentrations by 31% while increasing carbamazepine epoxide concentrations by 57%, potentially reducing carbamazepine efficacy. The mechanism involves felbamate increases carbamazepine metabolism and epoxide formation. 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
- Felbamate Class
- Anti-epileptic Agent
- Carbamazepine Class
- Mood Stabilizer
- Management
- Close medical supervision required
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Felbamate and Carbamazepine occurs because felbamate increases carbamazepine metabolism and epoxide formation. Clinically, this means felbamate decreases steady-state carbamazepine plasma concentrations by 31% while increasing carbamazepine epoxide concentrations by 57%, potentially reducing carbamazepine efficacy. 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 Felbamate and your doctor is considering prescribing Carbamazepine (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