erythromycin: clinical use

Prescribing considerations

• Confirm a susceptible or reasonably suspected bacterial indication and consider local resistance patterns.
• Review the medication list for CYP3A4-mediated and QT-prolonging interactions.
• Assess cardiac disease, bradycardia, conduction abnormalities, electrolyte disturbance and other arrhythmia risks.
• Use caution in hepatic impairment or with potentially hepatotoxic medicines.
• Erythromycin may worsen myasthenia gravis.
• In young infants, balance benefit against infantile hypertrophic pyloric stenosis risk and advise carers to report feeding-associated irritability or vomiting.

Contraindications and cautions

• Hypersensitivity to erythromycin or product excipients.
• Congenital or acquired QT prolongation, previous torsades de pointes or ventricular arrhythmia.
• Hypokalaemia or hypomagnesaemia.
• Concurrent ergotamine or dihydroergotamine.
• Concurrent use of listed high-risk medicines, including simvastatin, domperidone, pimozide, cisapride and certain antihistamines; product lists differ.

Monitoring

• Correct relevant electrolyte abnormalities and consider ECG assessment when cardiac risk factors or interacting medicines are present.
• Monitor for hepatic injury if symptoms arise or hepatic function is impaired.
• Monitor anticoagulation or bleeding when used with oral anticoagulants.
• Where relevant, monitor concentrations or toxicity of narrow-therapeutic-index interacting medicines.
• Investigate severe or persistent diarrhoea for antibiotic-associated colitis.

Clinical pharmacology

A systemic macrolide antibacterial that binds the 50S bacterial ribosomal subunit. It is absorbed from the small intestine, distributes widely, undergoes little metabolism and is eliminated mainly through the liver. It is also a clinically important CYP3A4 inhibitor.

Formulation and product differences

• Selected oral products are gastro-resistant or enteric-coated tablets intended to be swallowed whole.
• Excipients differ. One selected product contains Sunset Yellow and Ponceau Red, which may cause allergic reactions; check the exact pack.
• The gastro-resistant product is described as essentially sodium-free.

Gastro-resistant tablet

Route: Oral

Strengths: 250 mg

Tablet

Route: Oral

Strengths: 250 mg