Drug interactions
Erythromycin stearate + Memantine-donepezil
Severity: Major
Erythromycin stearate and Memantine-donepezil: major 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
Donepezil can prolong the QT interval and has been linked to torsades de pointes. Erythromycin stearate shares the QT-prolonging potential of erythromycin, so together they raise the risk of ventricular arrhythmia. CYP3A4 inhibition by erythromycin may also increase donepezil concentrations.
What this interaction means in plain words
Erythromycin stearate 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
Prefer an antibiotic without QT liability. If used together, obtain a baseline ECG, correct potassium and magnesium, and monitor for palpitations, syncope and QTc change.
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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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 stearate with Memantine-donepezil?
MediHelp rates the interaction as major. Erythromycin stearate 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 stearate shares the QT-prolonging potential of erythromycin, so together they raise the risk of ventricular arrhythmia. CYP3A4 inhibition by erythromycin may also increase donepezil concentrations.
How serious is the interaction between Erythromycin stearate 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: Prefer an antibiotic without QT liability. If used together, obtain a baseline ECG, correct potassium and magnesium, and monitor for palpitations, syncope and QTc change.
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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