Open-label, follow-on study of azithromycin in pediatric patients with CF uninfected with Pseudomonas aeruginosa

Background We previously performed a randomized placebo-controlled trial to examine the effects of azithromycin in children and adolescents 618 years of age with cystic fibrosis uninfected with Pseudomononas aeruginosa and demonstrated that while azithromycin did not acutely improve pulmonary function, azithromycin-reduced pulmonary exacerbations, decreased the initiation of new oral antibiotics, and improved weight gain. We now report the results of the open-label, follow-on study to assess durability of response to azithromycin and continued safety and tolerability. Methods Eligible participants were enrolled in a 24-week open-label study of azithromycin to compare efficacy and safety endpoints during the placebo-controlled trial versus open-label study in two groups: participants initially on azithromycin continued azithromycin (azithromycinazithromycin) and participants initially on placebo who then received azithromycin (placeboazithromycin). As in the placebo-controlled trial, the azithromycin dose in the open-label study was 250?mg MondayWednesdayFriday for participants weighing 1835.9?kg and 500?mg MondayWednesdayFriday for participants weighing 36?kg or greater. Results Of 174 eligible participants, 146 (83.9%) enrolled in the open-label study. No significant improvements in lung function were observed within either group. There were no differences in outcomes in the placeboazithromycin group during the placebo-controlled versus open-label phase. The azithromycinazithromycin group had comparable odds of experiencing an exacerbation during the two phases (OR 1.6, CI95 0.8, 3.0) and stable weight gain, but new oral antibiotics were initiated more frequently during the open-label study (OR 1.9, CI95 1.0, 3.5). In both groups, adverse event rates were comparable during the placebo-controlled and open-label study and treatment-emergent pathogens were rare. Conclusions During the open-label study, we observed continued durability of treatment response to azithromycin, as measured by pulmonary exacerbations and continued weight gain, although use of oral antibiotics increased. There were no new safety concerns. Currently available data suggest that azithromycin reduces exacerbations and improves weight gain for 612 months among children and adolescents with CF uninfected with P. aeruginosa. Pediatr Pulmonol. 2012; 47:641648. (C) 2012 Wiley Periodicals, Inc.