Drug interactions
Erythromycin ethylsuccinate + Memantine-donepezil
Severity: Major
Erythromycin ethylsuccinate and Memantine-donepezil: 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
Donepezil can prolong the QT interval and has been linked to torsades de pointes. Erythromycin is a macrolide with known QT-prolonging potential, so combined use increases the risk of serious ventricular arrhythmia. Erythromycin also inhibits CYP3A4, which may raise donepezil exposure.
What this interaction means in plain words
Erythromycin ethylsuccinate and Memantine-donepezil 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.
Why it happens
Additive QT prolongation through cardiac potassium channel effects, with possible CYP3A4 inhibition by erythromycin increasing donepezil levels.
What to do
Use a non-QT-prolonging antibiotic when possible. If combined, obtain a baseline ECG, correct potassium and magnesium, and monitor for QTc prolongation, bradycardia and syncope.
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 Memantine-donepezil
- Dronedarone + Memantine-donepezil Contraindicated
- Memantine-donepezil + Thioridazine Contraindicated
- Amantadine + Memantine-donepezil Major
- Amiodarone + Memantine-donepezil Major
- Amisulpride + Memantine-donepezil Major
- Amitriptyline + Memantine-donepezil Major
Frequently asked questions
Can I take Erythromycin ethylsuccinate with Memantine-donepezil?
MediHelp rates the interaction as major. Erythromycin ethylsuccinate and Memantine-donepezil 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. Donepezil can prolong the QT interval and has been linked to torsades de pointes. Erythromycin is a macrolide with known QT-prolonging potential, so combined use increases the risk of serious ventricular arrhythmia. Erythromycin also inhibits CYP3A4, which may raise donepezil exposure.
How serious is the interaction between Erythromycin ethylsuccinate and Memantine-donepezil?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use a non-QT-prolonging antibiotic when possible. If combined, obtain a baseline ECG, correct potassium and magnesium, and monitor for QTc prolongation, bradycardia and syncope.
What other medicines interact with Memantine-donepezil?
MediHelp also lists interactions of Memantine-donepezil with, for example, Dronedarone, Thioridazine, Amantadine. The full list is on the Memantine-donepezil page.
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