What is the recommended dose of clarithromycin (antibiotic) for children?

Clarithromycin Dosing for Children

For children over 1 month of age, administer clarithromycin at 15 mg/kg/day divided into 2 doses (maximum 1 g/day), and avoid use in infants under 1 month due to unknown risk of infantile hypertrophic pyloric stenosis (IHPS). 1

Standard Pediatric Dosing

Age-Based Recommendations

• Infants under 1 month: Clarithromycin is not recommended due to potential association with IHPS, similar to erythromycin 1
• Children 1 month and older: 15 mg/kg/day divided into 2 doses, with a maximum daily dose of 1 g 1, 2
• Adolescents 12-18 years: 500 mg twice daily (adult dosing) 1

Weight-Based Oral Dosing (Children 1 month to 11 years)

The British Thoracic Society provides specific weight-based dosing for oral administration 1:

• Under 8 kg: 7.5 mg/kg twice daily 1
• 8-11 kg: 62.5 mg twice daily 1
• 12-19 kg: 125 mg twice daily 1
• 20-29 kg: 187.5 mg twice daily 1
• 30-40 kg: 250 mg twice daily 1

Intravenous Dosing

• Children 1 month to 11 years: 7.5 mg/kg (maximum 500 mg) twice daily via large proximal vein 1
• Children 12-18 years: 500 mg twice daily 1

Duration of Treatment

• Pertussis treatment: 7 days 1
• Respiratory tract infections: Typically 7-14 days depending on severity and clinical response 3, 4
• Mycobacterial infections: Extended duration as part of multidrug regimen 1

Available Formulations

• Oral tablets: 250 mg, 500 mg 1
• Oral suspension: 125 mg/5 mL, 250 mg/5 mL 1
• Parenteral: 500 mg powder for injection 1

Critical Safety Considerations

Contraindications and Cautions

• Absolute contraindication: History of hypersensitivity to any macrolide antibiotic 1
• Drug interactions: Clarithromycin inhibits CYP3A enzymes, leading to potentially dangerous interactions with drugs metabolized by this pathway, including carbamazepine, cyclosporine, tacrolimus, triazolam, alprazolam, and sildenafil 1, 5
• Concurrent medications to avoid: Do not administer with astemizole, cisapride, pimozide, or terfenadine due to risk of cardiac arrhythmias 1

Adverse Effects Monitoring

• Common gastrointestinal effects: Epigastric distress, abdominal cramps, nausea, vomiting, and diarrhea occur in 2-6% of patients 1, 6
• Serious but rare reactions: QTc prolongation, hepatotoxicity, Stevens-Johnson syndrome, and anaphylaxis 1
• Ototoxicity: Hearing loss and tinnitus can occur with long-term use 1

Required Monitoring

• Baseline ECG: Obtain before starting therapy 1
• Follow-up ECG: Repeat at 2 weeks and after adding any QT-prolonging medication 1
• Audiometry: Baseline assessment and repeat if symptoms develop 1
• Laboratory monitoring: Intermittent CBC, renal function, and liver function tests throughout treatment 1

Dosage Adjustments

Renal Impairment

• Dosage adjustment required in patients with severe renal impairment (creatinine clearance <30 mL/min), though specific pediatric guidelines are limited 1, 5
• No adjustment needed for isolated hepatic impairment with normal renal function 1

Higher Doses

• Research demonstrates that clarithromycin remains safe and well-tolerated even at doses exceeding 15 mg/kg/day, with some children receiving up to 30 mg/kg/day without significant increase in adverse events 6
• However, stick to the guideline-recommended 15 mg/kg/day maximum unless treating specific mycobacterial infections under specialist guidance 1, 2

Common Pitfalls to Avoid

• Underdosing: Ensure the full 15 mg/kg/day is prescribed, as lower doses may lead to treatment failure 2, 4
• Overlooking drug interactions: Always review concurrent medications before prescribing, particularly those metabolized by CYP3A 1, 5
• Using in neonates: Never use in infants under 1 month due to IHPS risk 1
• Ignoring QT prolongation risk: Obtain baseline ECG in patients with cardiac risk factors or those on other QT-prolonging medications 1
• Forgetting pregnancy category: Clarithromycin is FDA Pregnancy Category C (animal studies show fetal harm), unlike erythromycin which is Category B 1