Comparison of 5 days of extended-release clarithromycin versus 10 days of penicillin V for the treatment of streptococcal pharyngitis/tonsillitis: results of a multicenter, double-blind, randomized study in adolescent and adult patients.

Objective: This study compared a short-course of clarithromycin with a standard course of penicillin V in patients with tonsillopharyngitis caused by Streptococcus pyogenes.
Research Design and Methods: A total of 539 patients, aged 12-75 years, were randomized to receive either clarithromycin extended-release (ER) 500 mg once daily for 5 days or penicillin V 500 mg three times daily for 10 days in this multicenter, double-blind, parallel-group trial. Eligibility required a positive antigen test for group A beta-hemolytic streptococcus (GABHS) followed by confirmatory culture.
Main Outcome Measures: Bacteriological and clinical assessments were conducted at each study visit (visit 1: study day 1; visit 2: study day 3; visit 3: study days 8-12; visit 4: study days 13-20; and visit 5: study days 40-50).
Results: At the test-of-cure visit (visit 3 for clarithromycin ER patients and visit 4 for penicillin V patients) in per-protocol patients, 5 days of clarithromycin ER was comparable to 10 days of penicillin V in eradicating S. pyogenes (89% (157/177) vs 90% (139/154) respectively; 95% CI for difference (-8.2, 5.1)). Bacterial eradication was sustained in both treatment groups at the follow-up visit (88% (135/153) vs 91% (112/123) respectively; 95% CI for difference (-10.0, 4.4)). Clinical cure was achieved in > or = 94% of patients in each treatment group. The most commonly reported study drug-related adverse events (< or = 3% in either treatment group) were abdominal pain, diarrhea, dyspepsia and nausea.
Conclusion: Clarithromycin ER 500 mg once daily for 5 days is equally effective as penicillin V 500 mg three times daily for 10 days in the treatment of adolescent and adult patients with streptococcal tonsillopharyngitis.