clarithromycin: clinical use

Prescribing considerations

• Confirm that the pathogen and infection site are appropriate, considering local resistance and microbiology results.
• Review all medicines for CYP3A4, P-glycoprotein, OATP and QT-related interactions.
• Assess renal and hepatic function when impairment is known or suspected.
• Use cautiously in coronary disease, heart failure, bradycardia, conduction disorders, myasthenia gravis or previous antibiotic-associated colitis.
• Check excipients where relevant: selected suspensions contain sucrose and aspartame; the prolonged-release product contains lactose.

Contraindications and cautions

• Hypersensitivity to clarithromycin, another macrolide or a product excipient.
• Known congenital or acquired QT prolongation, previous ventricular arrhythmia, hypokalaemia or hypomagnesaemia.
• Severe hepatic failure combined with renal impairment.
• Concurrent use with contraindicated medicines including simvastatin, lovastatin, colchicine, oral midazolam, domperidone, ergot alkaloids, ticagrelor, ivabradine, ranolazine or lomitapide.
• Significant renal impairment for the selected prolonged-release formulation because suitable adjustment cannot be made.

Monitoring

• Renal and hepatic function where clinically indicated; stop and assess if hepatitis symptoms develop.
• ECG and potassium or magnesium in patients with arrhythmia risk or interacting QT-prolonging treatment.
• INR and bleeding signs with warfarin; assess bleeding risk with direct oral anticoagulants.
• Blood glucose with insulin or glucose-lowering medicines.
• Effects or concentrations of narrow-therapeutic-index interacting medicines where appropriate; monitor muscle symptoms if a compatible statin continues.
• Investigate severe, persistent or delayed diarrhoea for antibiotic-associated colitis.

Clinical pharmacology

A semisynthetic macrolide that inhibits bacterial protein synthesis by binding the 50S ribosomal subunit. It is hepatically metabolised to an active 14-hydroxy metabolite and inhibits CYP3A4 and several drug transporters.

Formulation and product differences

• Immediate-release tablets may be taken with or without food and include an H. pylori eradication indication in combination therapy.
• Prolonged-release tablets must be taken with food and swallowed intact; they are unsuitable when substantial renal adjustment is required.
• Oral suspensions are intended principally for younger children, must be shaken before measurement and may contain sucrose or aspartame.
• Intravenous products are for hospital use and must be diluted and infused, not given as a bolus or intramuscular injection.

Solution for infusion

Route: Intravenous

Strengths: 500 mg

Modified-release tablet

Route: Oral

Strengths: 500 mg

Oral suspension

Route: Oral

Strengths: 125 mg/5 mL, 250 mg/5 mL