Drug interactions
Disopyramide + Promethazine
Severity: Major
Disopyramide and Promethazine: major interaction.
Last updated Sources: Base de donnees publique des medicaments (France)
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, and combining them raises the risk of torsades de pointes and other ventricular arrhythmias. Disopyramide carries a notable proarrhythmic risk by itself.
What this interaction means in plain words
Disopyramide and Promethazine 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.
Disopyramide belongs to Cardiovascular; Promethazine belongs to Respiratory.
Why it happens
Additive QT prolongation through cardiac potassium channel blockade.
What to do
Avoid the combination where possible and choose a non-QT-prolonging antiemetic or antihistamine. If unavoidable, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc.
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 Promethazine
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
Other interactions of Disopyramide
- Amisulpride + Disopyramide Contraindicated
- Desipramine + Disopyramide Contraindicated
- Disopyramide + Dronedarone Contraindicated
- Disopyramide + Itraconazole Contraindicated
- Disopyramide + Ketoconazole Contraindicated
- Disopyramide + Maprotiline Contraindicated
Frequently asked questions
Can I take Disopyramide with Promethazine?
MediHelp rates the interaction as major. Disopyramide and Promethazine 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, and combining them raises the risk of torsades de pointes and other ventricular arrhythmias. Disopyramide carries a notable proarrhythmic risk by itself.
How serious is the interaction between Disopyramide and Promethazine?
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 antiemetic or antihistamine. If unavoidable, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Cabergoline, Dopamine, Ibutilide. The full list is on the Promethazine page.
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