Drug interactions
Istradefylline + Quinidine
Severity: Moderate
Istradefylline and Quinidine: 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 daily istradefylline raised exposure to CYP3A4 and P-gp substrates, so quinidine concentrations may increase. Because quinidine has a narrow therapeutic index, this may raise the risk of toxicity including QT prolongation.
What this interaction means in plain words
Istradefylline and Quinidine 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; Quinidine belongs to Anti Parasitic.
Why it happens
Istradefylline inhibits CYP3A4 and P-glycoprotein, reducing quinidine clearance.
What to do
Monitor ECG and quinidine levels, and consider a quinidine dose reduction if istradefylline 40 mg daily is used.
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 Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Other interactions of Istradefylline
Frequently asked questions
Can I take Istradefylline with Quinidine?
MediHelp rates the interaction as moderate. Istradefylline and Quinidine 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 daily istradefylline raised exposure to CYP3A4 and P-gp substrates, so quinidine concentrations may increase. Because quinidine has a narrow therapeutic index, this may raise the risk of toxicity including QT prolongation.
How serious is the interaction between Istradefylline and Quinidine?
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 ECG and quinidine levels, and consider a quinidine dose reduction if istradefylline 40 mg daily is used.
What other medicines interact with Quinidine?
MediHelp also lists interactions of Quinidine with, for example, Adagrasib, Arsenic trioxide, Artemether / lumefantrine. The full list is on the Quinidine page.
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