Drug interactions
Erythromycin stearate + Primaquine
Severity: Major
Erythromycin stearate and Primaquine: major interaction.
Last updated Sources: US FDA label
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, so giving them together may raise the risk of torsades de pointes, particularly with electrolyte disturbance or underlying heart disease. Erythromycin is a recognised QT-prolonging macrolide.
What this interaction means in plain words
Erythromycin stearate and Primaquine 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 prolongation of cardiac repolarisation through potassium channel (hERG) effects.
What to do
Prefer a non-QT-prolonging antibiotic when possible. If both are required, obtain a baseline ECG, correct potassium and magnesium, and monitor the 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 Primaquine
- Pimozide + Primaquine Contraindicated
- Amiodarone + Primaquine Major
- Amisulpride + Primaquine Major
- Anagrelide + Primaquine Major
- Arsenic trioxide + Primaquine Major
- Asenapine + Primaquine Major
Frequently asked questions
Can I take Erythromycin stearate with Primaquine?
MediHelp rates the interaction as major. Erythromycin stearate and Primaquine 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, so giving them together may raise the risk of torsades de pointes, particularly with electrolyte disturbance or underlying heart disease. Erythromycin is a recognised QT-prolonging macrolide.
How serious is the interaction between Erythromycin stearate and Primaquine?
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 a non-QT-prolonging antibiotic when possible. If both are required, obtain a baseline ECG, correct potassium and magnesium, and monitor the QTc.
What other medicines interact with Primaquine?
MediHelp also lists interactions of Primaquine with, for example, Pimozide, Amiodarone, Amisulpride. The full list is on the Primaquine page.
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