Clarithromycin Dosage Recommendations
For adults, the recommended dosage of clarithromycin is 500 mg twice daily for most infections, with duration varying from 7-14 days depending on the specific infection being treated. 1, 2
Standard Adult Dosing
- For immediate-release formulation: 500 mg twice daily (total 1 g per day) 1, 3
- For extended-release formulation: 1 g once daily (two 500 mg tablets), should be taken with food 1, 4
- Extended-release tablets should be swallowed whole; do not chew, break or crush 1
Infection-Specific Dosing and Duration
Respiratory Infections
- Acute bacterial exacerbation of chronic bronchitis: 1 g extended-release daily for 7 days 1
- Community-acquired pneumonia: 1 g extended-release daily for 7 days 1
- Acute maxillary sinusitis: 1 g extended-release daily for 14 days 1
Helicobacter pylori Infection
- Standard triple therapy: 500 mg twice daily for 14 days (with PPI and amoxicillin or metronidazole) 2
- Sequential therapy: 500 mg twice daily (during second 5-day period of 10-day regimen) 2
Mycobacterial Infections
- Mycobacterium avium complex: 500 mg twice daily with ethambutol (15 mg/kg daily) 2
Lyme Disease
- 500 mg twice daily for 14-21 days (for patients intolerant to first-line agents) 2
Pertussis (Whooping Cough)
- Adults: 1 g per day in two divided doses for 7 days 2
- Children >1 month: 15 mg/kg per day (maximum: 1 g per day) in 2 divided doses for 7 days 2
- Not recommended for infants <1 month of age 2
Dosage Adjustments
Renal Impairment
- Moderate impairment (CrCl 30-60 mL/min): Reduce dosage by 50% 1, 5
- Severe impairment (CrCl <30 mL/min): Reduce dosage by 50-75% 1, 5
- For patients on atazanavir or ritonavir with renal impairment: Reduce dosage by 50-75% 1
Drug Interactions
- Reduce clarithromycin dose by 50% when co-administered with atazanavir 1
- Consider dose reduction when used with CYP3A inhibitors (e.g., ritonavir) 1, 5
- Rifabutin toxicity is common when combined with clarithromycin; consider reducing rifabutin dose 2
Pediatric Dosing
- Children >1 month: 15 mg/kg/day divided into 2 doses (maximum 1 g/day) 2
- For NTM infections in children 1 month-11 years: 7.5 mg/kg twice daily (max 500 mg per dose) 2
- Weight-based dosing for children 1 month-11 years 2:
- Under 8 kg: 7.5 mg/kg twice daily
- 8-11 kg: 62.5 mg twice daily
- 12-19 kg: 125 mg twice daily
- 20-29 kg: 187.5 mg twice daily
- 30-40 kg: 250 mg twice daily
Important Considerations
- Clarithromycin is contraindicated in patients with history of hypersensitivity to macrolide antibiotics 2
- Should not be administered with astemizole, cisapride, pimazole, or terfenadine due to risk of cardiac arrhythmias 2, 5
- Inhibits cytochrome P450 (CYP3A) enzymes, leading to multiple potential drug interactions 2, 5
- Common adverse effects include gastrointestinal symptoms (abdominal pain, diarrhea, nausea, vomiting, and taste perversion) 2, 4
- Extended-release formulation may have better gastrointestinal tolerability than immediate-release 4
- Take extended-release tablets with food to maximize bioavailability 4