Randomized, double-blind, double-dummy study comparing the efficacy and safety of amoxycillin 1 g bd with amoxycillin 500 mg tds in the treatment of acute exacerbations of chronic bronchitis.

This randomized, multicentre, double-blind, double-dummy study compared the efficacy and safety of amoxycillin 1 g bd with amoxycillin 500 mg tds in 395 patients with a clinical diagnosis of acute exacerbation of chronic bronchitis (AECB). Patients were treated for 10 days and were assessed during therapy (days 3-5), after the end of therapy (days 12-15) and at follow up (days 28-35). In the intention-to-treat (ITT) population, clinical success rates at the end of therapy were 86.6% (162/187 patients) and 85.6% (161/188 patients) in the bd and tds group, respectively. In the per-protocol (PP) subgroup, the success rates were 89.1% (156/175) and 92.6% (150/162), respectively. The clinical recurrence rates at follow up were, in the ITT and PP populations, respectively, 14.2% (20/141) and 13.4% (18/134) in the bd group, and 12.6% (18/143) and 13.7% (18/131) in the tds group. The 95% confidence intervals (CI) confirmed the clinical equivalence of the two dosage regimens in the ITT and PP populations. Two hundred and nineteen patients from the clinically evaluable ITT population had at least one pathogen isolated at baseline and were evaluable for bacteriological efficacy. Bacteriological success at the end of therapy was obtained in 76.2% (83/109) of patients in the bd group, and 73.7% (81/110) of patients in the tds group (95% CI: -9 to 14%). The most frequently reported drug-related adverse events in the safety evaluable patients were gastrointestinal symptoms, which occurred in 11.2% (22/197) in the bd group and 11.6% (23/198) in the tds group. Amoxycillin 1 g bd is clinically and bacteriologically as effective as amoxycillin 500 mg tds in the treatment of AECB, and the two dosage regimens show a similar safety profile.