Drug interactions
Ondansetron + Primidone
Severity: Minor
Ondansetron and Primidone: minor 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
Primidone, partly via its metabolite phenobarbital, induces CYP3A4 and CYP1A2 and may reduce ondansetron exposure. Enzyme inducers have been shown to lower ondansetron levels, though dose changes are usually not required.
What this interaction means in plain words
Ondansetron and Primidone have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Ondansetron belongs to Gastrointestinal Tract; Primidone belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 and CYP1A2 by primidone/phenobarbital increases ondansetron clearance.
What to do
No empirical dose change is needed. Monitor antiemetic response and adjust therapy if control is inadequate.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Ondansetron
- Apomorphine + Ondansetron Contraindicated
- Ondansetron + Thioridazine Contraindicated
- Ondansetron + Vandetanib Contraindicated
- Adagrasib + Ondansetron Major
- Amiodarone + Ondansetron Major
- Amisulpride + Ondansetron Major
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Ondansetron with Primidone?
MediHelp rates the interaction as minor. Ondansetron and Primidone have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Primidone, partly via its metabolite phenobarbital, induces CYP3A4 and CYP1A2 and may reduce ondansetron exposure. Enzyme inducers have been shown to lower ondansetron levels, though dose changes are usually not required.
How serious is the interaction between Ondansetron and Primidone?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No empirical dose change is needed. Monitor antiemetic response and adjust therapy if control is inadequate.
What other medicines interact with Ondansetron?
MediHelp also lists interactions of Ondansetron with, for example, Apomorphine, Thioridazine, Vandetanib. The full list is on the Ondansetron page.
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