Clinical efficacy of dirithromycin in pharyngitis and tonsillitis.

A total of 193 patients with streptococcal pharyngitis/tonsillitis received 500 mg dirithromycin once daily and 196 patients 250 mg erythromycin four times daily for ten days in a double-blind, parallel-group multicentre study. In the dirithromycin treatment group, 97 (50.3%) patients completed the study and were evaluated for efficacy analysis, and 99/196 (50.5%) erythromycin-treated were evaluated for efficacy of treatment. Favourable clinical responses to treatment (cure or improvement of symptoms) at the post-therapy visit (three to five days after therapy completion) occurred in 89 (91.7%) dirithromycin- and 93 (93.9%) erythromycin-treated patients. Bacteriological response was favourable (pathogen eliminated in 81 (83.5%) dirithromycin- and 87 (87.9%) erythromycin-treated patients. At late post-therapy (three to five weeks after treatment) 82/89 (92.1%) dirithromycin- and 90/93 (96.8%) erythromycin-treated patients had a favourable clinical response. Bacteriological response at late post-therapy was favourable in 77 (86.5%) dirithromycin- and 85 (94.4%) erythromycin-treated patients. No deaths occurred during or after treatment, and the serious events experienced by three dirithromycin- and one erythromycin-treated patients were unrelated to treatment. Five patients taking dirithromycin and seven taking erythromycin discontinued treatment prematurely, mainly due to gastrointestinal disturbances. Adverse events that occurred in 2% or more of patients in each treatment group were mainly gastrointestinal (diarrhoea, abdominal pain, nausea and vomiting); headache and rash were also reported. No significant differences in clinical laboratory data were detected that were considered to be drug-related.