Drug interactions
Memantine-donepezil + Thioridazine
Severity: Contraindicated
Memantine-donepezil and Thioridazine: contraindicated 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 cause torsades de pointes, and thioridazine is a strongly QT-prolonging antipsychotic. Together the arrhythmia risk is increased. Donepezil-induced bradycardia adds to the risk.
What this interaction means in plain words
Memantine-donepezil and Thioridazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Memantine-donepezil belongs to Central Nervous System; Thioridazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with cholinesterase-inhibitor bradycardia increasing torsades susceptibility.
What to do
Avoid the combination; choose a non-QT-prolonging antipsychotic such as low-dose quetiapine if needed, with ECG monitoring.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Memantine-donepezil
Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Memantine-donepezil with Thioridazine?
MediHelp rates the interaction as contraindicated. Memantine-donepezil and Thioridazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Donepezil can prolong the QT interval and cause torsades de pointes, and thioridazine is a strongly QT-prolonging antipsychotic. Together the arrhythmia risk is increased. Donepezil-induced bradycardia adds to the risk.
How serious is the interaction between Memantine-donepezil and Thioridazine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination; choose a non-QT-prolonging antipsychotic such as low-dose quetiapine if needed, with ECG monitoring.
What other medicines interact with Memantine-donepezil?
MediHelp also lists interactions of Memantine-donepezil with, for example, Dronedarone, Amantadine, Amiodarone. The full list is on the Memantine-donepezil page.
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