Drug interactions
Istradefylline + Lapatinib
Severity: Moderate
Istradefylline and Lapatinib: 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 the 40 mg daily dose, istradefylline raises exposure to CYP3A4 and P-gp substrates, which may increase lapatinib levels and its toxicity. The effect was not seen at 20 mg daily.
What this interaction means in plain words
Istradefylline and Lapatinib 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; Lapatinib belongs to Oncology.
Why it happens
Istradefylline inhibits CYP3A4 and P-glycoprotein, reducing lapatinib clearance and efflux.
What to do
Keep istradefylline at 20 mg daily where possible and monitor for lapatinib adverse effects such as diarrhea, liver injury and QT changes.
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 Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Other interactions of Istradefylline
Frequently asked questions
Can I take Istradefylline with Lapatinib?
MediHelp rates the interaction as moderate. Istradefylline and Lapatinib 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 the 40 mg daily dose, istradefylline raises exposure to CYP3A4 and P-gp substrates, which may increase lapatinib levels and its toxicity. The effect was not seen at 20 mg daily.
How serious is the interaction between Istradefylline and Lapatinib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Keep istradefylline at 20 mg daily where possible and monitor for lapatinib adverse effects such as diarrhea, liver injury and QT changes.
What other medicines interact with Lapatinib?
MediHelp also lists interactions of Lapatinib with, for example, Dofetilide, Ibutilide, Pimozide. The full list is on the Lapatinib page.
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