Randomized, double-blind, multicenter safety and efficacy study of rifalazil compared with azithromycin for treatment of uncomplicated genital Chlamydia trachomatis infection in women

Abstract

A randomized, double-blind study comparing single-dose chlamydia therapies of oral rifalazil (25 mg) and azithromycin (1 g) was conducted in 82 women with uncomplicated genital Chlamydia trachomatis infection. The microbiologic cure rate of C. trachomatis with rifalazil (n = 33) was 84.8% at the visit on day 22 to 26 (test-of-cure visit), versus 92.1% with azithromycin (n = 38), and the number of treatment failures in each group was 5 and 3, respectively. The difference in cure rate was -7.3%, with a lower limit of the 95% confidence interval (95% CI) of -22.5, and thus, noninferiority was not established at the prespecified margin (lower limit of CI of -15%). The overall treatment-emergent adverse event (TEAE) and treatment-related TEAE rates were lower in the rifalazil group (68% and 55%) than in the azithromycin group (71% and 62%), respectively. Subjects classified as treatment failures at day 22 to 26 had a lower mean plasma concentration of rifalazil at the visit on day 8 to 12 than those classified as treatment cures, but this difference was not significant; however, the levels were similar for both groups at the visit on day 22 to 26. A single 25-mg dose of rifalazil was well tolerated and eradicated C. trachomatis in most of these women with uncomplicated genital C. trachomatis infection. (The study was registered at clinicaltrials.gov under registration no. NCT01631201).

FIG 1

Disposition of subjects.

FIG 2

Rifalazil plasma concentration by cure or noncure. Box plot summaries of rifalazil plasma concentrations (dots) in women cured versus the concentrations in those not cured at visit 2 (day 8 to 12) (left) and visit 3 (day 22 to 26) (right). Box lines represent median values and interquartile ranges. Also shown are dashed lines connecting mean plasma concentrations (⊗) of those cured and not cured at the respective visits.