Drug interactions
Promethazine + Ranolazine
Severity: Moderate
Promethazine and Ranolazine: moderate 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
Ranolazine causes dose-related QT prolongation and promethazine can add to this effect. The combination may increase the risk of ventricular arrhythmias, especially in patients with structural heart disease.
What this interaction means in plain words
Promethazine and Ranolazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Promethazine belongs to Respiratory; Ranolazine belongs to Cardiovascular.
Why it happens
Additive QT prolongation.
What to do
Obtain a baseline ECG, correct electrolyte abnormalities, and monitor QTc during combined use; consider an alternative antiemetic.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Other interactions of Ranolazine
- Adagrasib + Ranolazine Contraindicated
- Amobarbital + Ranolazine Contraindicated
- Apalutamide + Ranolazine Contraindicated
- Butabarbital + Ranolazine Contraindicated
- Carbamazepine + Ranolazine Contraindicated
- Clarithromycin + Ranolazine Contraindicated
Frequently asked questions
Can I take Promethazine with Ranolazine?
MediHelp rates the interaction as moderate. Promethazine and Ranolazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Ranolazine causes dose-related QT prolongation and promethazine can add to this effect. The combination may increase the risk of ventricular arrhythmias, especially in patients with structural heart disease.
How serious is the interaction between Promethazine and Ranolazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG, correct electrolyte abnormalities, and monitor QTc during combined use; consider an alternative antiemetic.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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