EXECUTIVE SUMMARY
Results of a new study, conducted by researchers at the University of Alabama at Birmingham, the University of Southern California, and the Los Angeles County Department of Health Services, confirm that azithromycin remains effective in the treatment of urogenital chlamydia.
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The Centers for Disease Control and Prevention recommends oral administration of 1 g of azithromycin in a single dose or 100 mg of doxycycline twice daily for seven days for the treatment of chlamydia infection.
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Azithromycin Requires Only One Dose, While Doxycycline Requires Patients To Take Multiple Pills Over Seven Days. Research Indicates That Patients Are Much More Likely To Adhere To Therapy When Taking A Single Dose Compared To Multiple Doses Over Time.
Results of a new study, conducted by researchers at the University of Alabama at Birmingham (UAB), the Los Angeles-based University of Southern California, and the Los Angeles County Department of Health Services, confirm that azithromycin remains effective in the treatment of urogenital chlamydia.1
To conduct the study, the research team compared two of the most commonly used medications for urogenital chlamydia: a single dose of azithromycin versus doxycycline given twice daily for seven days. Data indicate azithromycin had a cure rate of 97%, compared to a 100% cure rate for doxycycline.1
The goal of the trial was to look at the efficacies of azithromycin and doxycycline regimens for urogenital chlamydia treatment using a study design that could control for limitations of many of the chlamydia treatment randomized controlled trials (RCTs) held previously, says William Geisler, MD, professor in the Division of Infectious Diseases in the UAB Department of Medicine and principle investigator of the study. These limitations included difficulty controlling for re-exposure to chlamydia-infected partners, difficulty with treatment nonadherence, and using a less sensitive chlamydia test.
“The reason that azithromycin was the focus of evaluating for noninferiority compared with doxycycline was that there had been a few recent studies (with chlamydia treatment data) that have used a more sensitive chlamydia test than earlier chlamydia treatment RCTs and showed azithromycin cure rates to be lower than expected based on a meta-analysis of the earlier RCTs,” Geisler stated in an email interview with Contraceptive Technology Update.
The study was conducted among adolescents in youth correctional facilities to evaluate the noninferiority of azithromycin (1 g in one dose) compared to doxycycline (100 mg twice daily for seven days).
The study was designed with the primary endpoint as treatment failure at 28 days after treatment initiation, with treatment failure determined on the basis of nucleic acid amplification testing, sexual history, and outer membrane protein A genotyping of C. trachomatis strains. Data were collected by Los Angeles County study staff, managed by FHI 360, a Durham, NC-based nonprofit human development organization, and analyzed by co-authors from the University of Arkansas for Medical Sciences in Little Rock. The study was funded by the Division of Microbiology and Infectious Diseases of the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.
Among the 567 participants enrolled, 284 were randomly assigned to receive azithromycin, and 283 were randomly assigned to receive doxycycline. Analysis of the data indicates there were no treatment failures in the doxycycline group. In the azithromycin group, treatment failure occurred in five participants (3.2%; 95% confidence interval, 0.4 to 7.4%). The observed difference in failure rates between the treatment groups was 3.2 percentage points, with an upper boundary of the 90% confidence interval of 5.9 percentage points, which exceeded the prespecified absolute 5-percentage-point cutoff for establishing the noninferiority of azithromycin.1
Studies of sexually transmitted infections can be difficult to do, because medical providers often cannot monitor adherence to a drug regimen, the researchers note. Also, a successfully treated patient can become re-infected, often from the same partner, during therapy. The design of the current study allowed scientists to control for all the complicated variables that had hindered previous research projects of this nature, Geisler notes.
“Our study subjects were separated from previous partners and had limited sexual exposure,” observed Geisler in a statement accompanying the study publication. “This approach allowed us to truly understand how well these drugs worked.”
CHECK TREATMENT OPTIONS
The Centers for Disease Control and Prevention (CDC) recommends oral administration of 1 g of azithromycin in a single dose or 100 mg of doxycycline twice daily for seven days for the treatment of chlamydia infection.2
Nonadherence to doxycycline therapy can contribute to treatment failure. In one study, researchers reported no treatment failures among 58 participants who took 10-14 doses, as compared with treatment failure in four of 20 participants (20%) who took fewer than 10 doses.3 In another study that evaluated doxycycline adherence among males with symptomatic chlamydia urethritis, data indicate treatment failure in one of 37 participants (3%) who took 14 doses, versus two of 10 participants (20%) who missed at least one dose.4
For providers, knowing whether azithromycin is an effective treatment option is important because patient adherence to therapy with doxycycline can be an issue, noted Geisler. Azithromycin requires only one dose, while doxycycline requires patients to take multiple pills over seven days. Studies have shown that patients are much more likely to adhere to therapy when taking a single dose compared to multiple doses over time.5
REFERENCES
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Geisler WM, Uniyal A, Lee JY, et al. Azithromycin versus doxycycline for urogenital Chlamydia trachomatis infection. N Engl J Med 2015; 373(26):2512-2521.
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Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep 2015; 64(No. RR-3):1-137.
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Bachmann LH, Stephens J, Richey CM, et al. Measured versus self-reported compliance with doxycycline therapy for chlamydia-associated syndromes: High therapeutic success rates despite poor compliance. Sex Transm Dis 1999; 26:272-278.
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Khosropour CM, Manhart LE, Colombara DV, et al. Suboptimal adherence to doxycycline and treatment outcomes among men with non-gonococcal urethritis: A prospective cohort study. Sex Transm Infect 2014; 90:3-7.
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Brown MT, Bussell JK. Medication adherence: WHO cares? Mayo Clinic Proceedings 2011; 86(4):304-314.
