Recommended Clarithromycin Dosage for Atypical Pneumonia
For atypical pneumonia, clarithromycin should be administered at 500 mg twice daily or as extended-release 1,000 mg once daily. 1, 2
Dosage Recommendations Based on Patient Setting
Outpatient Treatment
- For healthy outpatients with suspected atypical pneumonia, clarithromycin 500 mg twice daily or clarithromycin extended-release 1,000 mg daily is recommended 1
- The extended-release formulation should be taken with food and swallowed whole (not crushed or chewed) 2
- Treatment duration is typically 7-14 days, depending on clinical response 3, 2
Patients with Comorbidities
- For outpatient adults with comorbidities (chronic heart, lung, liver, or renal disease; diabetes; alcoholism; malignancy; asplenia), clarithromycin may be used as part of combination therapy 1
- In these patients, clarithromycin (500 mg twice daily or extended-release 1,000 mg once daily) is combined with a beta-lactam such as amoxicillin/clavulanate 1, 3
Special Considerations
Renal Impairment
- For patients with severe renal impairment (CrCl <30 mL/min), reduce the clarithromycin dosage by 50% 2
- For patients with moderate renal impairment (CrCl 30-60 mL/min) taking concomitant atazanavir or ritonavir, reduce the clarithromycin dosage by 50% 2
- For patients with severe renal impairment taking concomitant atazanavir or ritonavir, reduce the clarithromycin dosage by 75% 2
Efficacy Against Atypical Pathogens
- Clarithromycin is highly effective against the major atypical pneumonia pathogens including Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella species 4
- Clinical trials have demonstrated high efficacy rates (>90%) for clarithromycin in treating atypical pneumonia 5, 6
Treatment Duration
- For most cases of community-acquired pneumonia including atypical pneumonia, a 7-day course of clarithromycin is sufficient 2, 7
- Shorter courses (5-7 days) have shown similar efficacy to longer courses (10 days) in clinical trials 7, 6
Comparative Efficacy
- Clarithromycin has similar clinical efficacy to other antibiotics used for atypical pneumonia, including azithromycin and respiratory fluoroquinolones 7, 6
- A 3-day course of azithromycin has been shown to be as effective as a 10-day course of clarithromycin for mild to moderate community-acquired pneumonia 6
- Clarithromycin has better gastrointestinal tolerability compared to erythromycin 4
Common Pitfalls and Caveats
- Macrolide monotherapy (including clarithromycin) should be avoided in areas with high pneumococcal resistance to macrolides (≥25%) 1, 3
- Drug interactions related to the cytochrome P450 system may occur with clarithromycin use, requiring dose adjustments of concomitant medications 2, 4
- Clarithromycin is contraindicated in patients with known hypersensitivity to macrolide antibiotics 2
- For patients not improving on initial therapy, consider adding or changing to a different antibiotic class 3