Drug interactions
Glibenclamide + Phenobarbital
Severity: Moderate
Glibenclamide and Phenobarbital: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Phenobarbital induces hepatic enzymes including CYP2C9 and CYP3A4, which can speed glyburide clearance. This may lower glyburide levels and reduce glycemic control.
What this interaction means in plain words
Glibenclamide and Phenobarbital can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Induction of CYP2C9 and CYP3A4 increases glyburide metabolism.
What to do
Monitor blood glucose when phenobarbital is started or stopped. Increase the glyburide dose if needed, and watch for hypoglycemia after phenobarbital is withdrawn.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Glibenclamide
- Bosentan + Glibenclamide Contraindicated
- Cholic acid + Glibenclamide Major
- Ciprofloxacin + Glibenclamide Major
- Clarithromycin + Glibenclamide Major
- Fluconazole + Glibenclamide Major
- Glibenclamide + Insulin degludec-liraglutide Major
Frequently asked questions
Can I take Glibenclamide with Phenobarbital?
MediHelp rates the interaction as moderate. Glibenclamide and Phenobarbital can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phenobarbital induces hepatic enzymes including CYP2C9 and CYP3A4, which can speed glyburide clearance. This may lower glyburide levels and reduce glycemic control.
How serious is the interaction between Glibenclamide and Phenobarbital?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood glucose when phenobarbital is started or stopped. Increase the glyburide dose if needed, and watch for hypoglycemia after phenobarbital is withdrawn.
What other medicines interact with Glibenclamide?
MediHelp also lists interactions of Glibenclamide with, for example, Bosentan, Cholic acid, Ciprofloxacin. The full list is on the Glibenclamide page.
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