Comparison of once- and twice-daily clarithromycin in the treatment of adults with severe acute lower respiratory tract infections

Background: Although the modified-release (MR) formulation of clarithromycin has demonstrated bioequivalence to the immediate-release (IR) formulation and thus can be prescribed for lower respiratory tract infections (LRTIs), a MEDLINE search from 1995 through 1998 and information on file with the manufacturer indicate that no data are available on the effectiveness of this new formulation in the treatment of severe LRTIs such as community-acquired pneumonia. Objective: This study was designed to compare clinical success rates (percentage of patients with clinical cure or improvement) With once- and twice-daily regimens of clarithromycin in the treatment of patients with severe, acute LRTIs requiring oral antibiotic therapy. Methods: In this multicenter, investigator-blinded, randomized, parallel-group study, adult patients with clinical evidence suggesting severe, acute LRTI were recruited from 22 general practices, in the United Kingdom. Patients were randomly allocated to receive either clarithromycin 500 mg BID (IR tablets) or clarithromycin I g OD (two 500-mg MR tablets) for 7 to 14 days. The outcome measures were resolution of or improvement in clinical signs and symptoms (including resolution of cough), unscheduled visits for the same symptom, days to resumption of normal activities, and improvements in quality of life (assessed using the EQ-5D version of the EuroQoL questionnaire). Clinical, microbiologic, and serologic assessments were performed before, during, and after treatment. Efficacy and safety data were analyzed on an intent-to-treat basis. Results: One hundred sixty men (n = 83) and women (n = 77) between the ages of 19 and 88 years took part in the study, 78 receiving clarithromycin 500 mg BID and 82 receiving clarithromycin 1 g OD. At 4 weeks after the start of treatment, the high clinical success rates were comparable between groups: 84.6% with clarithromycin 500 mg BID and 90.2% with clarithromycin 1 g OD. No significant differences in outcome measures were noted between the 2 regimens. Both treatments were well tolerated, with taste disturbance being the most commonly reported adverse event (10.6% vs 6.1% with clarithromycin 500 mg BID and 1 g OD, respectively). Conclusions: The 2 clarithromycin regimens were equally efficacious and well tolerated in the treatment of severe, acute LRTIs. However, caution should be exercised in applying these results to the general population, because the study excluded certain categories of patients who would normally be treated. In addition, the small sample size may have obscured clinically significant differences between the 2 regimens.