Five-day dirithromycin therapy is as effective as seven-day erythromycin therapy for acute exacerbations of chronic bronchitis

In a meta-analysis of two identically designed, well-controlled, randomized, double-blind clinical trials, we compared 5 days of dirithromycin with 7 days of erythromycin for acute exacerbations of chronic bronchitis. Five hundred and thirty-one patients were randomized to receive dirithromycin (500 mg od) for 5 days and 526 patients were randomized to receive erythromycin (250 mg qid) for 7 days. Clinical and bacteriological responses were assessed 3-5 days after therapy and at termination from the study. Adverse events were collected from both groups and compared with each other, before and after treatment. Of the 690 patients clinically appraisable at the post-therapy visit, 298 (84.2%) dirithromycin-treated patients and 270 (80.4%) erythromycin-treated patients showed a favourable response. At termination, 273 (77.1%) dirithromycin-treated patients and 243 (72.3%) erythromycin-treated patients showed a favourable response. The microbiological cure was equivalent in the two groups (75% of dirithromycin-treated patients and 74.1% of erythromycin-treated patients showed a favourable response at termination). After therapy, dirithromycin was as effective as erythromycin in eradicating Streptococcus pneumoniae (77.8% vs 90.9%), Haemophilus influenzae (71.7% vs 72.2%), Moraxella catarrhalis (93.3% vs 88.9%) and Staphylococcus aureus (81.8% vs 82.1%). Although not statistically significant, fewer dirithromycin-treated patients reported adverse events than did erythromycin-treated patients. Nausea (6.8% vs 7.8%), headache (7.3% vs 8.2%) and diarrhoea (6.6% vs 9.5%) were the most frequently reported adverse events in both groups. In the treatment of acute exacerbations of chronic bronchitis, 5 days of dirithromycin is as effective as 7 days of erythromycin.