The efficacy of azithromycin was similar, though not noninferior, to doxycycline for the treatment of urogenital Chlamydia trachomatis infection, according to recent data.
During a recent investigation, 97% of patients who received azithromycin were cured of chlamydia, according to William M. Geisler, MD, professor in the division of infectious diseases at the University of Alabama at Birmingham, and colleagues. Geisler, a co-author of CDC’s chlamydia guidelines, said in a press release that the drug should be considered as a front-line therapy.
William M. Geisler
“Recent studies have raised concerns over the efficacy of azithromycin, and there has not been a definitive, well-controlled randomized clinical trial of its effectiveness,” Geisler said in the release. “For physicians, knowing whether azithromycin is an effective treatment option is important because patient adherence to therapy with doxycycline can be an issue. Azithromycin requires only one dose, while doxycycline requires patients to take multiple pills over 7 days.”
Treatment efficacy was assessed in 567 participants aged 12 to 21 years who resided in one of four long-term youth correctional facilities in Los Angeles. The researchers randomly assigned 284 participants to azithromycin and 283 participants to doxycycline between December 2009 and April 2014. The primary outcome was treatment failure, which was defined as a positive test for concordant chlamydia strains at baseline and follow-up.
Fifty-five percent of participants in each arm of the study completed the first follow-up. No treatment failures were reported in the doxycycline arm (95% CI, 0.0-2.4); however, five asymptomatic patients (four males, one female) in the azithromycin arm tested positive for chlamydia at follow-up (3.2%; 95% CI, 0.4-7.4). The failure rate differed by 3.2% between the groups (one-sided 90% CI, 0-5.9).
“Because the upper boundary of the 90% confidence interval exceeded 5 percentage points…the noninferiority of azithromycin to doxycycline was not established,” Geisler and colleagues wrote. “This was not a result of azithromycin having low efficacy. Rather, it reflected the 100% efficacy of doxycycline.”
Ninety percent of participants in the azithromycin arm and 81% in the doxycycline arm completed the second follow-up. One treatment failure was identified in a female participant from the azithromycin arm who tested negative at the first follow-up, but was positive for chlamydia during the second follow-up.
Adverse events were similar regardless of treatment allocation. Twenty-three percent of participants in the azithromycin arm reported adverse events vs. 27% in the doxycycline arm. The most frequent adverse events were gastrointestinal symptoms.
“The bottom line is that our results show that both medications are effective in the treatment of chlamydia, and that while azithromycin had a limited number of treatment failures, the adherence to the drug regimen is likely to be much greater with the single-dose drug as opposed to the multidose doxycycline,” Geisler said in the release. – by Stephanie Viguers
Disclosure: Geisler reports receiving grants from ActivBiotics Pharma.