Drug interactions
Asenapine + Phenobarbital
Severity: Moderate
Asenapine 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 and asenapine both cause sedation, and together they may produce marked drowsiness, impaired alertness and respiratory depression at higher doses. Phenobarbital is also an enzyme inducer that may modestly lower asenapine exposure.
What this interaction means in plain words
Asenapine 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
Additive CNS depression; phenobarbital may induce CYP-mediated metabolism of asenapine.
What to do
Monitor for oversedation and for loss of antipsychotic effect, and adjust the asenapine dose by clinical response. Counsel patients on driving and alcohol avoidance.
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 Asenapine
- Asenapine + Pimozide Contraindicated
- Asenapine + Thioridazine Contraindicated
- Asenapine + Vandetanib Contraindicated
- Adagrasib + Asenapine Major
- Alfentanil + Asenapine Major
- Alfuzosin + Asenapine Major
Frequently asked questions
Can I take Asenapine with Phenobarbital?
MediHelp rates the interaction as moderate. Asenapine 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 and asenapine both cause sedation, and together they may produce marked drowsiness, impaired alertness and respiratory depression at higher doses. Phenobarbital is also an enzyme inducer that may modestly lower asenapine exposure.
How serious is the interaction between Asenapine 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 for oversedation and for loss of antipsychotic effect, and adjust the asenapine dose by clinical response. Counsel patients on driving and alcohol avoidance.
What other medicines interact with Asenapine?
MediHelp also lists interactions of Asenapine with, for example, Pimozide, Thioridazine, Vandetanib. The full list is on the Asenapine page.
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