title: Once-daily azithromycin for 3 days compared with clarithromycin for 10 days for acute exacerbation of chronic bronchitis: a multicenter, double-blind, randomized study.
abstract: OBJECTIVE
  To compare the efficacy and safety of oral azithromycin 500 mg once daily for 3 days with those of oral clarithromycin 500 mg twice daily for 10 days.
  
  
  METHODS
  Randomized, double-blind, double-dummy, multicenter study.
  
  
  METHODS
  Seventy-six study centers in eight countries (Argentina, Brazil, Canada, Chile, Costa Rica, India, South Africa, and USA).
  
  
  METHODS
  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.
  
  
  METHODS
  Randomization 1 : 1 to azithromycin 500 mg once daily for 3 days or clarithromycin 500 mg twice daily for 10 days.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  Three-day treatment with azithromycin 500 mg once daily is equivalent to a 10-day treatment with clarithromycin 500 mg twice daily in adult patients with AECB.
authors.affiliation: Pfizer Global Research & Development, Groton, Connecticut, USA.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Swanson
authors.forename: Alberto
authors.initials: A
authors.lastname: Lainez-Ventosilla
authors.forename: Maria C
authors.initials: MC
authors.lastname: De Salvo
authors.forename: Michael W
authors.initials: MW
authors.lastname: Dunne
authors.forename: Guy W
authors.initials: GW
authors.lastname: Amsden
mesh_terms: D000208:Acute Disease; D000284:Administration, Oral; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D017963:Azithromycin / Q000008:administration & dosage*; D029481:Bronchitis, Chronic / Q000188:drug therapy* / Q000382:microbiology; D017291:Clarithromycin / Q000008:administration & dosage*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006193:Haemophilus influenzae / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D001936:Moraxella catarrhalis / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000302:isolation & purification; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D017963:Azithromycin; D017291:Clarithromycin