An open-label, randomized, multicenter, comparative study of the efficacy and safety of 7 days of treatment with clarithromycin extended-release tablets versus clarithromycin immediate-release tablets for the treatment of patients with acute bacterial exacerbation of chronic bronchitis

Objective: The aim of this study was to compare the efficacy and safety of clarithromycin extended-release (ER) tablets and immediate-release (IR) tablets. Methods: This was a Phase 111, open-label, randomized, multicenter, comparative study in ambulatory patients with a diagnosis of acute exacerbation of chronic bronchitis (AECB). Eligible patients were randomized 1:1 to receive either I clarithromycin ER 500-mg tablet QD for 7 days or I clarithromycin IR 250-mg tablet BID for 7 days. Clinical and bacteriologic responses were assessed within 48 hours after the last dose of study drug and at a test-of-cure visit 21 +/- 2 days posttreatment. Results: Of 233 patients randomized, 162 (86/117 [73.5%] in the ER group and 76/115 [66.1%] in the IR group) completed the study protocol. Compliance did not differ significantly between the treatment groups; however, significantly fewer patients in the ER group reported missing doses of study medication than in the IR group (7/118 [5.9%] vs 16/115 [13.9%]; P = 0.04). The clinical cure rates for the clarithromycin ER and IR groups were 81.0% (68/84) and 82.1% (64/78) and the clinical success (clinical cure plus clinical improvement) rates were 94.0% [79/84] and 89.7% [70/78], respectively. There were insufficient data for analysis of bacteriologic efficacy. However, bacteria were eradicated or presumed eradicated in 71.4% (10/14) and 79.2% (19/24) of patients in the ER and IR groups, respectively. The number of adverse events (AEs) considered to be possibly or probably related to study drug (23.4% [52/222] of patients receiving clarithromycin ER and 24.4% [43/176] of patients receiving clarithromycin IR) was similar between groups, as was the severity of these events (94.2% [49/52] in the ER group classified as mild or moderate vs 93.0% [40/43] in the IR group). Overall, the most commonly reported AEs were diarrhea, nausea, abdominal pain, headache, and taste disturbance. Conclusion: Clarithromycin ER 500-mg tablets QD for 7 days were as effective and well tolerated as clarithromycin IR 250-mg tablets BID for 7 days in treating adults with AECB.