Multicenter evaluation of azithromycin and cefaclor in acute lower respiratory tract infections.

This was a randomized, third-party-blinded, multicenter study that compared once-daily azithromycin (500 mg on day 1, followed by 250 mg on days 2-5) to cefaclor (500 mg three times daily for 10 days) in the treatment of patients with acute bronchitis or pneumonia. A total of 546 patients were entered into the study and 272 patients were evaluable for efficacy analysis. Of these, 249 (176 azithromycin, 73 cefaclor) had bronchitis and 23 (15 azithromycin, 8 cefaclor) had pneumonia. The combined clinical cure and improvement rate, as determined by the investigator, was 96% for azithromycin and 94% for cefaclor, with 88% bacteriologic eradication in both treatment groups. The elimination of Haemophilus influenzae was significantly better with azithromycin (94.5%) than with cefaclor (61.1%) (p less than 0.001; Fisher's exact two-tail test). The two antibiotics were well tolerated during this study; the incidence of side effects reported was similar for azithromycin and cefaclor. Approximately two thirds of the side effects were mild. Only minor abnormalities in the screening laboratory tests were noted. This study shows that a 5-day course of once-daily azithromycin is as effective as a 10-day three times daily course of cefaclor in the treatment of patients with acute lower respiratory tract infections.