Comparative Efficacy of Once Daily, 5-Day Short-Course Therapy With Clarithromycin Extended-Release Versus Twice Daily, (RedNova) Key words: Acute bacterial exacerbation * Chronic bronchitis * Clarithromycin * Extended-release ABSTRACT Objective: The objective of this study was to compare the efficacy, tolerability, and safety of two clarithromycin regimens, extended-release (ER) 1000mg once daily for 5 days and immediate- release (IR) 500 mg twice daily for 7 days, in the treatment of acute bacterial exacerbation of