Comparative study of dirithromycin and azithromycin in the treatment of acute bacterial exacerbations of chronic bronchitis

We compared the clinical and microbiological efficacy of dirithromycin with that of azithromycin in outpatients with acute bacterial exacerbations of chronic bronchitis who could be graded into stage III according to Ball's s ystem of stratification. A total of 80 patients was studied. Of these, 40 w ere treated with dirithromycin as a once-daily dose of 500 mg for 5 days, a nd 40 with azithromycin as a once-daily dose of 500 mg for 3 days. At post- therapy, treatment success (cure or improvement) was achieved in 36 out of 40 (90%) patients receiving dirithromycin compared with 37 out of 40 (92.5% ) in the azithromycin group. At the late post-therapy visit, 34 out of 36 ( 94.4%) dirithromycin-treated patients were cured as were 33 of 37 (89.2%) a zithromycin-treated patients. A small proportion of patients treated with d irithromycin (10%) or with azithromycin (12.5%) suffered mild side effects. Gastrointestinal disorders, including abdominal cramps, nausea, or diarrhe a, were common adverse effects. The main pathogens isolated before treatmen t were Streptococcus pneumoniae, Haemophilus influenzas, and Moraxella cata rrhalis. Eradication rates at the end of treatment were 90% (36 out of 40) for the dirithromycin group and 92.5% (37 out of 40) for the azithromycin g roup. Persistence of H. influenzae isolates was found in 3 out of 11 (27.3% ) patients treated with dirithromycin and in 2 out of 9 (22.2%) who had rec eived azithromycin. At the late post-therapy visit, eradication occurred in 34 out of 36 (94.4%) strains in the dirithromycin group and in 33 out of 3 7 (89.2%) in the azithromycin group. We conclude that dirithromycin and azi thromycin appear to be equally effective in the treatment of acute bacteria l exacerbations of chronic bronchitis.