Study Results

• What We Learned:

  This study found that azithromycin did not reduce the effect of inhaled tobramycin on lung function. Over the course of the 6-week study, including 4 weeks of inhaled tobramycin, participants taking azithromycin (n=56) had an average change in FEV1L of 1.69% (0.6% change in percent predicted FEV1). Those given placebo (n=52) had an average change in FEV1L of -1.95% (-1.9% change in percent predicted FEV1). Change in lung function (FEV1) was the primary outcome of this study and did not significantly differ between those given azithromycin or placebo.

   

  Among a subset of the overall study cohort (n=64), the change in P. aeruginosa density in sputum samples was also tested. Over the course of the 6-week study those taking azithromycin had an average increase in P. aeruginosa density of 0.3 log10 CFU/mL. Those who received placebo had an average change of -0.49 log10 CFU/mL. This difference was statistically significant between the groups (difference 0.75, p=0.043).

   

   

• Primary Findings:

  Effectiveness:

  This study was conducted between October 2016 and December 2019. The study enrolled 119 participants and 115 received at least one dose of azithromycin or placebo (n=62 azithromycin and n=57 placebo). 7 participants withdrew during the randomized 6-week period (5 azithromycin and 2 placebo). Over 80% of people reported using azithromycin when entering the trial.

   

  The primary efficacy endpoint was the change in lung function, as measured by relative change in FEV1 liters, from baseline to week 6. Over the course of the 6 weeks, participants in the group taking azithromycin had an average relative change in lung function (FEV1 liters) of 1.69%, while participants in the placebo group had a -1.95% change (difference: 3.44%; 95% CI: -0.48, 7.35; p=0.085). The difference in percent predicted FEV1 was 2.28%; 95% CI: -0.42, 4.98; p=0.097.

   

   

  No significant differences between the two groups were seen in self-reported respiratory symptoms or weight during the 6-week study.

   

  The study did show that among a subset of participants with microbiology results available, among those who received azithromycin, there was an increase in P. aeruginosa on average (0.30 log10) during the 6 weeks while those that received placebo had a reduction in P. aeruginosa (-0.49 log10) (difference: 0.75 log10; 95% CI: 0.03, 1.47; p=0.043) from baseline to end of inhaled tobramycin at week 6.

  Safety:

  No significant differences occurred between those randomized to azithromycin or placebo in rate of acute pulmonary exacerbations, need for additional antibiotics, or need to be in the hospital. The total number of all adverse events, mostly respiratory events, was higher in the placebo group.

• Citation:

  Thorax 2021;DOI 10.1136/thoraxjnl-2021-217782 [Epub ahead of print]

For current information about the overall development status of this drug, please check the Drug Development Pipeline.