Treatments in Respiratory Medicine

, Volume 4, Issue 1, pp 31–39

Once-Daily Azithromycin for 3 Days Compared with Clarithromycin for 10 Days for Acute Exacerbation of Chronic Bronchitis

A Multicenter, Double-Blind, Randomized Study


  • Robert N. Swanson
    • Pfizer Global Research & Development
  • Alberto Lainez-Ventosilla
    • Instituto Costarricense de Investigaciones Clinicas (ICIC), Urbanizacion Los ArbolesFrente al Centro Nacional de Rehabilitacion (CENARE)
  • Maria C. De Salvo
    • Hospital General de Agudos
  • Michael W. Dunne
    • Pfizer Global Research & Development
    • Clinical Pharmacology Research Center, Bassett Healthcare
Original Research Article

DOI: 10.2165/00151829-200504010-00004

Cite this article as:
Swanson, R.N., Lainez-Ventosilla, A., De Salvo, M.C. et al. Treat Respir Med (2005) 4: 31. doi:10.2165/00151829-200504010-00004


Study objectives

To compare the efficacy and safety of oral azithromycin 500mg once daily for 3 days with those of oral clarithromycin 500mg twice daily for 10 days.


Randomized, double-blind, double-dummy, multicenter study.


Seventy-six study centers in eight countries (Argentina, Brazil, Canada, Chile, Costa Rica, India, South Africa, and USA).


Three hundred and twenty-two adult outpatients with acute exacerbation of chronic bronchitis (AECB) as documented by increased cough or sputum production, worsening dyspnea, and purulent sputum production.


Randomization 1: 1 to azithromycin 500mg once daily for 3 days or clarithromycin 500mg twice daily for 10 days.


The primary efficacy endpoint was clinical response at day 21–24, or test of cure (TOC) visit in the modified intent-to-treat (MITT) analysis (n = 318 patients). The TOC clinical cure rates in the MITT population were equivalent in the two treatment groups at 85% with azithromycin and 82% with clarithromycin (95% CI–5.9%, 12.0%). Clinical success rates on day 10–12 were also equivalent at 93% with azithromycin and 94% with clarithromycin (95% CI–7.9%, 4.4%). Clinical cure rates at TOC by pathogen were equivalent for the two treatment groups for Haemophilus influenzae (azithromycin, 85.7%; clarithromycin, 87.5%), Moraxella catarrhalis (91.7% and 80.0%, respectively) and Streptococcus pneumoniae (90.6% and 77.8%, respectively). Bacteriologic success rates were also equivalent between the azithromycin and clarithromycin treatment groups at TOC for S. pneumoniae (90.6% and 85.2%, respectively), H. influenzae (71.4% and 81.3%, respectively) and M. catarrhalis (100% and 86.7%, respectively). The overall incidence of treatment-related adverse events was similar in the azithromycin and clarithromycin groups (20.9% and 26.8%, respectively), with the most common being abdominal pain (6.3% and 6.1%, respectively), diarrhea (4.4% and 5.5%, respectively), and nausea (4.4% and 3.7%, respectively).


Three-day treatment with azithromycin 500mg once daily is equivalent to a 10-day treatment with clarithromycin 500mg twice daily in adult patients with AECB.

Copyright information

© Adis Data Information BV 2005