Efficacy of ciprofloxacin and clarithromycin in acute bacterial exacerbations of complicated chronic bronchitis: interim analysis. Bronchitis Study Group.

In a multicenter, community-based study involving more than 300 primary care physicians in the United States, the efficacy and safety of ciprofloxacin and clarithromycin were compared in the treatment of patients with complicated or severe acute bacterial exacerbations of chronic bronchitis (i.e., those who had failed previous antibiotic treatment within the prior 2 to 4 weeks; those with susceptibility data suggestive of a resistant pathogen; those having three or more acute exacerbations of chronic bronchitis [AECB] within the past year; and those having three or more comorbid conditions). Patients were randomized to either ciprofloxacin (CIP) 750 mg BID or clarithromycin (CLR) 500 mg BID, both administered for 10 days; all patients were treated on an outpatient basis. Clinical response at the end of therapy was the primary efficacy variable. An interim analysis was performed on the results from 743 patients (369 CIP, 374 CLR) with clinical and bacteriologic evidence of a bronchopulmonary infection who had completed an ongoing study as of the end of May 1997. Three hundred nine pathogens were isolated before therapy, including Haemophilus spp (75 isolates), Moraxella catarrhalis (67 isolates), Staphylococcus aureus (55 isolates), and Streptococcus pneumoniae (23 isolates). Seven hundred eighteen patients (97%) were included in the efficacy-valid population. Clinical success at the end of therapy was observed in 90% (272 of 302) and 88% (274 of 313) of efficacy-valid patients treated with CIP and CLR, respectively (95% confidence interval [CI] = -2.4 to 7.6). Corresponding rates for the intent-to-treat population were also 90% (283 of 314) and 88% (281 of 321), respectively (95% CI = -2.3 to 7.5). The bacteriologic response for efficacy-valid patients at the end of therapy was 98% (119 of 122) for CIP-treated and 93% (103 of 111) for CLR-treated patients (95% CI = -0.8 to 10.2). The eradication rates for the three most commonly isolated gram-negative pathogens were 100% for CIP-treated and 95% for CLR-treated patients and 96% each for the two most commonly isolated gram-positive organisms. Superinfections due to respiratory tract pathogens were more common in the CLR group (10 organisms) than in the CIP group (4 organisms). Seventy-four (20%) CIP-treated and 62 (17%) CLR-treated patients reported 118 and 103 respective study-emergent adverse events. Headache, abdominal pain, diarrhea, nausea, and vomiting in CIP-treated patients and diarrhea, nausea, vomiting, and taste perversion in CLR-treated patients were the most commonly reported adverse events. Treatment of patients with complicated or severe AECB with CIP 750 mg BID was associated with rates of clinical success and bacteriologic eradication similar to those with CLR.