Drug interactions
Guanfacine + Lapatinib
Severity: Moderate
Guanfacine and Lapatinib: 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
Lapatinib may increase guanfacine concentrations by inhibiting CYP3A4, leading to hypotension, bradycardia and sedation.
What this interaction means in plain words
Guanfacine and Lapatinib 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.
Guanfacine belongs to Cardiovascular; Lapatinib belongs to Oncology.
Why it happens
Inhibition of CYP3A4 metabolism of guanfacine by lapatinib.
What to do
Reduce extended-release guanfacine to half the recommended dose per labeling. Monitor blood pressure, heart rate and sedation.
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
Other interactions of Guanfacine
- Clonidine + Guanfacine Major
- Guanfacine + Lofexidine Major
- Aldesleukin + Guanfacine Moderate
- Amiodarone + Guanfacine Moderate
- Amisulpride + Guanfacine Moderate
- Amitriptyline + Guanfacine Moderate
Frequently asked questions
Can I take Guanfacine with Lapatinib?
MediHelp rates the interaction as moderate. Guanfacine and Lapatinib 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. Lapatinib may increase guanfacine concentrations by inhibiting CYP3A4, leading to hypotension, bradycardia and sedation.
How serious is the interaction between Guanfacine and Lapatinib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Reduce extended-release guanfacine to half the recommended dose per labeling. Monitor blood pressure, heart rate and sedation.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
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