Drug interactions
Erythromycin lactobionate + Perphenazine
Severity: Major
Erythromycin lactobionate and Perphenazine: major interaction.
Last updated Sources: Health Canada product monograph
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
Intravenous erythromycin is a recognized QT-prolonging agent, and with perphenazine the risk of torsades de pointes is increased. Higher IV concentrations make this concern more relevant.
What this interaction means in plain words
Erythromycin lactobionate and Perphenazine 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.
Erythromycin lactobionate belongs to Anti Bacterial; Perphenazine belongs to Central Nervous System.
Why it happens
Additive blockade of cardiac IKr potassium channels, with possible CYP3A4 inhibition by erythromycin.
What to do
Use an alternative antibiotic if possible. If the combination is required, check a baseline ECG, correct electrolytes, and monitor the QTc during therapy.
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 Perphenazine
- Ibutilide + Perphenazine Contraindicated
- Perphenazine + Pimozide Contraindicated
- Perphenazine + Thioridazine Contraindicated
- Adagrasib + Perphenazine Major
- Alfentanil + Perphenazine Major
- Amiodarone + Perphenazine Major
Other interactions of Erythromycin lactobionate
- Cisapride + Erythromycin lactobionate Contraindicated
- Dihydroergotamine + Erythromycin lactobionate Contraindicated
- Dronedarone + Erythromycin lactobionate Contraindicated
- Eletriptan + Erythromycin lactobionate Contraindicated
- Ergotamine + Erythromycin lactobionate Contraindicated
- Erythromycin lactobionate + Flibanserin Contraindicated
Frequently asked questions
Can I take Erythromycin lactobionate with Perphenazine?
MediHelp rates the interaction as major. Erythromycin lactobionate and Perphenazine 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. Intravenous erythromycin is a recognized QT-prolonging agent, and with perphenazine the risk of torsades de pointes is increased. Higher IV concentrations make this concern more relevant.
How serious is the interaction between Erythromycin lactobionate and Perphenazine?
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 an alternative antibiotic if possible. If the combination is required, check a baseline ECG, correct electrolytes, and monitor the QTc during therapy.
What other medicines interact with Perphenazine?
MediHelp also lists interactions of Perphenazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Perphenazine page.
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