Drug interactions
Lapatinib + Trazodone
Severity: Major
Lapatinib and Trazodone: 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 inhibits CYP3A4 and prolongs the QT interval, and trazodone is a CYP3A4 substrate that can also prolong QT. The combination may increase trazodone exposure and the risk of arrhythmia including torsades de pointes.
What this interaction means in plain words
Lapatinib and Trazodone 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 belongs to Oncology; Trazodone belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with lapatinib CYP3A4 inhibition raising trazodone concentrations.
What to do
Avoid if possible; otherwise obtain a baseline ECG, correct electrolytes, monitor QTc and consider a lower trazodone dose.
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 Trazodone
- Arsenic trioxide + Trazodone Contraindicated
- Ibutilide + Trazodone Contraindicated
- Isocarboxazid + Trazodone Contraindicated
- Levoketoconazole + Trazodone Contraindicated
- Methylene blue + Trazodone Contraindicated
- Phenelzine + Trazodone Contraindicated
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 Lapatinib with Trazodone?
MediHelp rates the interaction as major. Lapatinib and Trazodone 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 inhibits CYP3A4 and prolongs the QT interval, and trazodone is a CYP3A4 substrate that can also prolong QT. The combination may increase trazodone exposure and the risk of arrhythmia including torsades de pointes.
How serious is the interaction between Lapatinib and Trazodone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid if possible; otherwise obtain a baseline ECG, correct electrolytes, monitor QTc and consider a lower trazodone dose.
What other medicines interact with Trazodone?
MediHelp also lists interactions of Trazodone with, for example, Arsenic trioxide, Ibutilide, Isocarboxazid. The full list is on the Trazodone page.
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