Drug interactions
Fentanyl transdermal + Lapatinib
Severity: Major
Fentanyl transdermal and Lapatinib: major 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
Lapatinib can inhibit CYP3A4 and may raise fentanyl concentrations. Because transdermal fentanyl has a long-lasting depot, the resulting respiratory depression may be prolonged.
What this interaction means in plain words
Fentanyl transdermal and Lapatinib can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
CYP3A4 inhibition by lapatinib reduces fentanyl clearance.
What to do
Monitor closely for respiratory depression and sedation for several days after starting or stopping lapatinib. Reduce the fentanyl dose or choose an opioid not dependent on CYP3A4.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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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
Frequently asked questions
Can I take Fentanyl transdermal with Lapatinib?
MediHelp rates the interaction as major. Fentanyl transdermal and Lapatinib can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Lapatinib can inhibit CYP3A4 and may raise fentanyl concentrations. Because transdermal fentanyl has a long-lasting depot, the resulting respiratory depression may be prolonged.
How serious is the interaction between Fentanyl transdermal and Lapatinib?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor closely for respiratory depression and sedation for several days after starting or stopping lapatinib. Reduce the fentanyl dose or choose an opioid not dependent on CYP3A4.
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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