Efficacy and safety of once-daily and twice-daily clarithromycin formulations in the treatment of acute exacerbations of chronic bronchitis

The broad-spectrum antibiotic clarithromycin has been shown to be safe and effective in the treatment of lower respiratory tract infections, including acute exacerbations of chronic bronchitis (AECB), when dosed at 250 or 500 mg twice daily. Because a once-daily schedule may improve compliance, a modified-release formulation of clarithromycin was developed. This prospective, double-blind, parallel-group, multicenter study randomized 239 patients to receive either clarithromycin modified-release tablets 500 mg once daily (CL MR) or clarithromycin tablets 250 mg twice daily (CL) for 7 to 14 days. At the end of treatment, 93% of evaluable and 91% of intent-to-treat (ITT) patients in the once-daily group and 95% and 90% of patients, respectively, in the twice-daily group achieved clinical success. At 21 days posttreatment, clinical success rates were 86% (evaluable) and 82% (ITT) with the once-daily formulation and 91% and 83% with the twice-daily formulation, Resolution or improvement of all symptoms occurred in 75% to 100% of patients in both groups. As measured by pill count, 96% and 94% of patients in the once- and twice-daily groups, respectively, were more than 90% compliant with their prescribed regimens. The most commonly reported adverse events were abdominal pain (9%) and diarrhea (4%) in the once-daily group and abdominal pain and headache (4% each) in the twice-daily group. CL MR is as effective as standard 250 mg CL given twice daily in the treatment of AECB. Both formulations were safe and well tolerated, and compliance with CL MR was slightly higher than with CL.