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Azithromycin Reduced Pulmonary Exacerbation Risk in Cystic Fibrosis

Azithromycin significantly reduced the risk for pulmonary exacerbations and resulted in sustained improvement in weight but had no effect on microbiologic outcomes in children with cystic fibrosis with early Pseudomonas aeruginosa infection, according to the results of a study published in the American Journal of Respiratory and Critical Care Medicine.

Nicole Mayer-Hamblett, PhD, professor, Department of Pediatrics and adjunct professor, Department of Biostatistics at the University of Washington and the Seattle Children's Hospital in Seattle, and colleagues analyzed data from the OPTIMIZE trial (Optimizing Treatment for Early Pseudomonas Aeruginosa Infection in Cystic Fibrosis; Identifier: NCT02054156) to determine whether complementing traditional antimicrobial therapy with tobramycin inhalation solution (TIS) would reduce the risk for pulmonary exacerbation and inflammation and thus ultimately prolong the time to P aeruginosa recurrence in patients with cystic fibrosis.

OPTIMIZE was a multicenter double-blind, placebo-controlled 18-month randomized clinical trial in children between the ages of 6 months and 18 years with cystic fibrosis and early P aeruginosa. Children received azithromycin or placebo 3 times weekly plus standard TIS. The primary end point of the study was time to pulmonary exacerbation requiring antibiotics, and the main secondary end point was the time to P aeruginosa recurrence.

A total 221 participants were enrolled in the study, 111 assigned to placebo and 110 assigned to azithromycin. Compared with placebo, the risk for a pulmonary exacerbation was reduced by 44% in participants who received azithromycin (hazard ratio, 0.56; P =.004). Weight increased by 1.27 kg in the azithromycin group compared with the placebo group (P =.046). The investigators noted no safety concerns and found no evidence of a negative clinical or microbiologic interaction between azithromycin and TIS. However, they found no significant benefit for the microbiologic end points.

The authors noted several study limitations. The trial ended early based on a prespecified interim analysis of efficacy for the primary end point, which may have limited information regarding the secondary end points. The authors are also awaiting future evaluation of inflammatory markers that will take place after the end of the open-label phase of the trial. This may help to explain how azithromycin decreases the risk for pulmonary exacerbations.

Despite the failure to find a delay in time to P aeruginosa recurrence, the authors believe that the long-term safety of azithromycin demonstrated here and the delay to pulmonary exacerbation suggests that azithromycin may be a therapeutic option for children with cystic fibrosis and early P aeruginosa infection.


Mayer-Hamblett N, Retsch-Bogart G, Kloster M, et al. Azithromycin for early pseudomonas infection in cystic fibrosis: the Optimize randomized trial [published online June 11, 2018]. Am J Respir Crit Care Med. doi:10.1164/rccm.201802-0215OC

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