Drug interactions
Istradefylline + Ondansetron
Severity: Minor
Istradefylline and Ondansetron: 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
At the 40 mg daily dose, istradefylline raises exposure to CYP3A4 and P-gp substrates, which could increase ondansetron levels. Ondansetron has several clearance routes, so the effect is expected to be modest, but QT-related dose-dependent effects could be amplified.
What this interaction means in plain words
Istradefylline and Ondansetron have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Istradefylline belongs to Central Nervous System; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Istradefylline at higher doses inhibits CYP3A4 and P-glycoprotein, reducing ondansetron clearance and efflux.
What to do
No routine ondansetron adjustment is needed at the 20 mg istradefylline dose. If the 40 mg dose is used, watch for ondansetron adverse effects such as headache, constipation and QT changes.
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 Istradefylline
Frequently asked questions
Can I take Istradefylline with Ondansetron?
MediHelp rates the interaction as minor. Istradefylline and Ondansetron have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. At the 40 mg daily dose, istradefylline raises exposure to CYP3A4 and P-gp substrates, which could increase ondansetron levels. Ondansetron has several clearance routes, so the effect is expected to be modest, but QT-related dose-dependent effects could be amplified.
How serious is the interaction between Istradefylline and Ondansetron?
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 routine ondansetron adjustment is needed at the 20 mg istradefylline dose. If the 40 mg dose is used, watch for ondansetron adverse effects such as headache, constipation and QT changes.
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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