Drug interactions
Clarithromycin + Pentamidine
Severity: Major
Clarithromycin and Pentamidine: major 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
Both clarithromycin and pentamidine can prolong the QT interval, and their combination has additive effects that may lead to torsades de pointes. The risk is greater with electrolyte disturbances, bradycardia or underlying heart disease.
What this interaction means in plain words
Clarithromycin and Pentamidine 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.
Clarithromycin belongs to Anti Bacterial; Pentamidine belongs to Anti Parasitic.
Why it happens
Additive pharmacodynamic QT prolongation through cardiac repolarization (hERG potassium channel) effects.
What to do
Avoid the combination where an alternative exists. If both are essential, obtain a baseline ECG, correct potassium and magnesium, 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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Other interactions of Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
Other interactions of Pentamidine
- Clomipramine + Pentamidine Contraindicated
- Desipramine + Pentamidine Contraindicated
- Dronedarone + Pentamidine Contraindicated
- Moxifloxacin + Pentamidine Contraindicated
- Nortriptyline + Pentamidine Contraindicated
- Pentamidine + Pimozide Contraindicated
Frequently asked questions
Can I take Clarithromycin with Pentamidine?
MediHelp rates the interaction as major. Clarithromycin and Pentamidine 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 clarithromycin and pentamidine can prolong the QT interval, and their combination has additive effects that may lead to torsades de pointes. The risk is greater with electrolyte disturbances, bradycardia or underlying heart disease.
How serious is the interaction between Clarithromycin and Pentamidine?
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 an alternative exists. If both are essential, obtain a baseline ECG, correct potassium and magnesium, and monitor the QTc during therapy.
What other medicines interact with Clarithromycin?
MediHelp also lists interactions of Clarithromycin with, for example, Astemizole, Avanafil, Cisapride. The full list is on the Clarithromycin page.
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