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
  • Alberto Lainez-Ventosilla
  • Maria C. De Salvo
  • Michael W. Dunne
  • Guy W. Amsden
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

Authors and Affiliations

  • Robert N. Swanson
    • 1
  • Alberto Lainez-Ventosilla
    • 2
  • Maria C. De Salvo
    • 3
  • Michael W. Dunne
    • 1
  • Guy W. Amsden
    • 4
  1. 1.Pfizer Global Research & DevelopmentGrotonUSA
  2. 2.Instituto Costarricense de Investigaciones Clinicas (ICIC), Urbanizacion Los ArbolesFrente al Centro Nacional de Rehabilitacion (CENARE)San JoseCosta Rica
  3. 3.Hospital General de AgudosBuenos AiresArgentina
  4. 4.Clinical Pharmacology Research Center, Bassett HealthcareCooperstownUSA

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