Drug interactions
Chlorpromazine + Lapatinib
Severity: Major
Chlorpromazine and Lapatinib: major interaction.
Last updated Sources: Health Canada product monograph
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
Both agents can prolong the QT interval, so the combination raises the risk of torsades de pointes. Risk increases with electrolyte abnormalities or other QT-prolonging factors.
What this interaction means in plain words
Chlorpromazine 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.
Chlorpromazine belongs to Central Nervous System; Lapatinib belongs to Oncology.
Why it happens
Additive prolongation of cardiac repolarization via cardiac potassium channel effects.
What to do
Check baseline ECG and electrolytes and correct any abnormalities. Monitor the ECG during therapy, or use an alternative antipsychotic with less QT effect.
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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References
Other interactions of Chlorpromazine
- Chlorpromazine + Dofetilide Contraindicated
- Chlorpromazine + Dronedarone Contraindicated
- Chlorpromazine + Droperidol Contraindicated
- Chlorpromazine + Ibutilide Contraindicated
- Chlorpromazine + Metrizamide Contraindicated
- Chlorpromazine + Panobinostat 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 Chlorpromazine with Lapatinib?
MediHelp rates the interaction as major. Chlorpromazine 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. Both agents can prolong the QT interval, so the combination raises the risk of torsades de pointes. Risk increases with electrolyte abnormalities or other QT-prolonging factors.
How serious is the interaction between Chlorpromazine 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: Check baseline ECG and electrolytes and correct any abnormalities. Monitor the ECG during therapy, or use an alternative antipsychotic with less QT effect.
What other medicines interact with Chlorpromazine?
MediHelp also lists interactions of Chlorpromazine with, for example, Dofetilide, Dronedarone, Droperidol. The full list is on the Chlorpromazine page.
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