Clarithromycin Dosing for Ear Infections
For acute otitis media in children, clarithromycin should be dosed at 15 mg/kg per day divided into two doses (maximum 1 g/day) for 7-10 days, which achieves excellent middle ear penetration and clinical cure rates of 93%. 1, 2
Pediatric Dosing (Primary Indication for Ear Infections)
Standard regimen:
- Children >1 month to 12 years: 15 mg/kg/day divided into 2 doses (maximum 1 g/day) for 7-10 days 3, 1, 2
- Alternative dosing: 7.5 mg/kg twice daily (maximum 500 mg per dose) 1, 4
- Infants <1 month: Not recommended due to unknown safety profile 3
Why This Dosing Works for Ear Infections
- Clarithromycin achieves mean middle ear effusion concentrations of 2.5 mg/L, which exceeds serum concentrations (1.7 mg/L) and surpasses MICs for most respiratory pathogens causing otitis media 4
- The active 14-hydroxy metabolite also penetrates well into middle ear fluid (1.3 mg/L), providing enhanced activity against Haemophilus influenzae 4
- Clinical cure/improvement rates of 93-95% are achieved within 4 days of treatment 1, 2
Adult Dosing (If Applicable)
Standard regimen:
- Adults: 500 mg twice daily for 7-14 days 3, 5
- Alternative: 1 g once daily using extended-release formulation 6
Key Clinical Considerations
Pathogen coverage:
- Excellent activity against Streptococcus pneumoniae, Moraxella catarrhalis, and Streptococcus pyogenes with complete nasopharyngeal eradication after 3 days 4
- Approximately 50% eradication of Haemophilus influenzae, with enhanced activity when parent drug and metabolite are combined 7, 4
Tolerability advantage:
- Gastrointestinal adverse effects occur in only 20% of children receiving clarithromycin versus 52% with amoxicillin-clavulanate (p<0.001) 2
- Adverse events are typically mild and transient, experienced by only 6% of children 4
Critical Safety Warnings
Absolute contraindications:
- History of hypersensitivity to any macrolide antibiotic 3, 5
- Concomitant use with astemizole, cisapride, pimozide, or terfenadine due to risk of cardiac arrhythmias including torsades de pointes 3, 5
Drug interactions:
- Clarithromycin inhibits CYP3A enzymes, leading to elevated concentrations of drugs metabolized by this pathway (e.g., carbamazepine, cyclosporine, digoxin, theophylline, warfarin) 3, 8
- Reduce clarithromycin dose by 50% when co-administered with ritonavir or lopinavir-ritonavir if CrCl <60 mL/min 9
Renal impairment:
- Reduce dose by 50% in severe renal impairment (CrCl <30 mL/min) 9, 8
- No adjustment needed for hepatic impairment or elderly patients 3, 8
Common Pitfalls to Avoid
- Do not exceed 1000 mg/day in children - doses above this are poorly tolerated 9
- Do not use in infants <1 month - safety not established and risk of infantile hypertrophic pyloric stenosis unknown 3
- Monitor for middle ear effusion persistence - effusion may persist despite clinical cure and does not necessarily indicate treatment failure 2
- Avoid aluminum/magnesium antacids - these reduce absorption rate of clarithromycin 3