Objective: The objective of this study was to compare the efficacy, tolerability, and safety of two clarithromycin regimens, extended-release (ER) 1000 mg once daily for 5 days and immediate-release (IR) 500 mg twice daily for 7 days, in the treatment of acute bacterial exacerbation of chronic bronchitis (ABECB).
Patients and methods: This was a double-blind, randomized, parallel-group, multicenter study of ambulatory patients at least 40 years old with a presumptive diagnosis of ABECB, purulent sputum, and documented evidence of chronic obstructive pulmonary disease (COPD), including forced expiratory volume in one second (FEV(1)) < 70% of predicted value. Clinical cure, bacteriological cure, and target pathogen eradication rates were determined at a test-of-cure visit (study days 14-40). Safety was assessed based on the incidence of study drug-related adverse events.
Results: A total of 485 patients were randomized (240 to ER and 245 to IR). Clinical cure rates were similar for evaluable patients treated with ER (84%, 157/187) and those treated with IR (84%, 172/204) (95% CI -7.9, 7.2). The bacteriological cure rates were 87% (82/94) and 89% (91/102), and the overall target pathogen eradication rates were 88% (107/122) and 89% (117/131) for the respective treatment groups. The incidence of adverse events was 13% (31/240) in the ER group and 18% (45/245) in the IR group. The rate of gastrointestinal adverse events was lower with ER (8%, 19/240) compared to IR (11%, 26/245). Clarithromycin ER-treated patients reported statistically significantly fewer adverse events due to abnormal taste than did clarithromycin IR-treated patients (3% and 8%, respectively, p = 0.012).
Conclusion: Both once-daily, 5-day, short-course therapy with clarithromycin ER and 7-day, twice-daily therapy with clarithromycin IR were effective in resolving clinical signs/symptoms of ABECB and eradicating the causative pathogens, with no statistically significant difference in clinical cure rate between the treatment groups. Clarithromycin ER was better tolerated, causing fewer gastrointestinal adverse events and statistically significantly fewer reports of abnormal taste as compared with clarithromycin IR.