Drug interactions
Lapatinib + Protriptyline
Severity: Moderate
Lapatinib and Protriptyline: 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
Both lapatinib and the tricyclic antidepressant protriptyline can prolong the QT interval. Used together, the additive effect raises the risk of torsades de pointes and other serious ventricular arrhythmias, especially with electrolyte disturbances or heart disease.
What this interaction means in plain words
Lapatinib and Protriptyline 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.
Why it happens
Additive pharmacodynamic QT prolongation through cardiac repolarization effects of both drugs.
What to do
Obtain a baseline ECG and correct potassium and magnesium before starting, then repeat ECGs periodically. Consider an alternative antidepressant if the QTc becomes markedly prolonged.
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
Frequently asked questions
Can I take Lapatinib with Protriptyline?
MediHelp rates the interaction as moderate. Lapatinib and Protriptyline 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. Both lapatinib and the tricyclic antidepressant protriptyline can prolong the QT interval. Used together, the additive effect raises the risk of torsades de pointes and other serious ventricular arrhythmias, especially with electrolyte disturbances or heart disease.
How serious is the interaction between Lapatinib and Protriptyline?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG and correct potassium and magnesium before starting, then repeat ECGs periodically. Consider an alternative antidepressant if the QTc becomes markedly prolonged.
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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