Drug interactions
Erythromycin + Selpercatinib
Severity: Major
Erythromycin and Selpercatinib: major interaction.
Last updated Sources: US FDA label
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 drugs can prolong the QT interval, so combining them may raise the risk of torsades de pointes. Erythromycin is also a moderate CYP3A4 inhibitor and may increase selpercatinib exposure.
What this interaction means in plain words
Erythromycin and Selpercatinib 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.
Erythromycin belongs to Anti Bacterial; Selpercatinib belongs to Oncology.
Why it happens
Additive QT prolongation, with erythromycin CYP3A4 inhibition potentially increasing selpercatinib concentrations.
What to do
Avoid the combination where possible and choose a non-QT-prolonging antibiotic. If unavoidable, monitor ECG and electrolytes and consider reducing the selpercatinib dose per labeling.
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 Erythromycin
- Conivaptan + Erythromycin Contraindicated
- Dihydroergotamine intranasal + Erythromycin Contraindicated
- Dihydroergotamine + Erythromycin Contraindicated
- Domperidone + Erythromycin Contraindicated
- Dronedarone + Erythromycin Contraindicated
- Droperidol + Erythromycin Contraindicated
Other interactions of Selpercatinib
Frequently asked questions
Can I take Erythromycin with Selpercatinib?
MediHelp rates the interaction as major. Erythromycin and Selpercatinib 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 drugs can prolong the QT interval, so combining them may raise the risk of torsades de pointes. Erythromycin is also a moderate CYP3A4 inhibitor and may increase selpercatinib exposure.
How serious is the interaction between Erythromycin and Selpercatinib?
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 where possible and choose a non-QT-prolonging antibiotic. If unavoidable, monitor ECG and electrolytes and consider reducing the selpercatinib dose per labeling.
What other medicines interact with Erythromycin?
MediHelp also lists interactions of Erythromycin with, for example, Conivaptan, Dihydroergotamine intranasal, Dihydroergotamine. The full list is on the Erythromycin page.
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