Drug interactions
Disopyramide + Lapatinib
Severity: Major
Disopyramide 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
Disopyramide is a class Ia antiarrhythmic known to cause torsades de pointes, and lapatinib also prolongs the QT interval. Combining them increases the risk of life-threatening ventricular arrhythmia.
What this interaction means in plain words
Disopyramide 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.
Disopyramide belongs to Cardiovascular; Lapatinib belongs to Oncology.
Why it happens
Additive pharmacodynamic QT prolongation.
What to do
Avoid the combination and choose an antiarrhythmic without QT effects if possible. If both are required, monitor the ECG and keep potassium and magnesium normal.
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 Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Other interactions of Disopyramide
- Amisulpride + Disopyramide Contraindicated
- Desipramine + Disopyramide Contraindicated
- Disopyramide + Dronedarone Contraindicated
- Disopyramide + Itraconazole Contraindicated
- Disopyramide + Ketoconazole Contraindicated
- Disopyramide + Maprotiline Contraindicated
Frequently asked questions
Can I take Disopyramide with Lapatinib?
MediHelp rates the interaction as major. Disopyramide 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. Disopyramide is a class Ia antiarrhythmic known to cause torsades de pointes, and lapatinib also prolongs the QT interval. Combining them increases the risk of life-threatening ventricular arrhythmia.
How serious is the interaction between Disopyramide 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: Avoid the combination and choose an antiarrhythmic without QT effects if possible. If both are required, monitor the ECG and keep potassium and magnesium normal.
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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