Drug interactions
Istradefylline + Tolvaptan
Severity: Moderate
Istradefylline and Tolvaptan: 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
At 40 mg/day, istradefylline inhibits CYP3A4 and P-gp and may increase tolvaptan exposure. This could result in excessive aquaresis, dehydration and rapid sodium correction.
What this interaction means in plain words
Istradefylline and Tolvaptan 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.
Istradefylline belongs to Central Nervous System; Tolvaptan belongs to Endocrine.
Why it happens
Istradefylline inhibits CYP3A4 metabolism and P-gp efflux of tolvaptan.
What to do
Monitor serum sodium and volume status, especially with istradefylline 40 mg/day. Consider reducing the tolvaptan dose if exaggerated response occurs.
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 Tolvaptan
- Atazanavir + Tolvaptan Contraindicated
- Ceritinib + Tolvaptan Contraindicated
- Cobicistat + Tolvaptan Contraindicated
- Conivaptan + Tolvaptan Contraindicated
- Darunavir + Tolvaptan Contraindicated
- Idelalisib + Tolvaptan Contraindicated
Other interactions of Istradefylline
Frequently asked questions
Can I take Istradefylline with Tolvaptan?
MediHelp rates the interaction as moderate. Istradefylline and Tolvaptan 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. At 40 mg/day, istradefylline inhibits CYP3A4 and P-gp and may increase tolvaptan exposure. This could result in excessive aquaresis, dehydration and rapid sodium correction.
How serious is the interaction between Istradefylline and Tolvaptan?
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 serum sodium and volume status, especially with istradefylline 40 mg/day. Consider reducing the tolvaptan dose if exaggerated response occurs.
What other medicines interact with Tolvaptan?
MediHelp also lists interactions of Tolvaptan with, for example, Atazanavir, Ceritinib, Cobicistat. The full list is on the Tolvaptan page.
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