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Doxycycline Prophylaxis to Prevent Sexually Transmitted Infections in Women, Editorial.
Why it didn't work for women?
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Download the PDF here
Download the PDF here
Editorial, original article pdfs attached
Dec 21 2023
Jenell Stewart et al.
"Among cisgender women, the incidence of STIs was not significantly lower with doxycycline PEP than with standard care. According to hair-sample analysis, the use of doxycycline PEP among those assigned to receive it was low."
Low detection of doxycycline among participants assigned to receive doxycycline PEP offers a primary explanation for the differing results between this trial and other studies of doxycycline PEP. Adherence......
Sexual network dynamics, including the number of partners, frequency of sexual exposures, and services for testing and treatment for partners, could contribute to differences between trials. women enrolled in the current trial did not have access to STI testing, and their medical history regarding STIs was unknown. Direct data on individual partners were not available.
Differences in primary infection sites are an important consideration for doxycycline prophylaxis; cisgender women more commonly have endocervical infections than rectal or pharyngeal infections. Recent evidence suggests that drug concentrations of doxycycline in the vagina are sufficient to prevent C. trachomatis, N. gonorrhoeae, and T. pallidum; peak concentrations were higher in vaginal mucosa, but time above the minimum inhibitory concentration was higher in rectal tissue.21 In the current trial, the presence of rectal or pharyngeal STIs was not measured, and thus it cannot be inferred whether doxycycline is protective at those sites in women.
Lack of efficacy for doxycycline to prevent N. gonorrhoeae infection is probably due in part to a high prevalence of high-level tetracycline-resistant (tet[M]) N. gonorrhoeae, an observation that is consistent with findings from previous studies conducted in Kenya.
Background
Doxycycline postexposure prophylaxis (PEP) has been shown to prevent sexually transmitted infections (STIs) among cisgender men and transgender women, but data from trials involving cisgender women are lacking.
Methods
We conducted a randomized, open-label trial comparing doxycycline PEP (doxycycline hyclate, 200 mg taken within 72 hours after condomless sex) with standard care among Kenyan women 18 to 30 years of age who were receiving preexposure prophylaxis against human immunodeficiency virus (HIV). The primary end point was any incident infection with Chlamydia trachomatis, Neisseria gonorrhoeae, or Treponema pallidum. Hair samples were collected quarterly for objective assessment of doxycycline use.
Results
A total of 449 participants underwent randomization; 224 were assigned to the doxycycline-PEP group and 225 to the standard-care group. Participants were followed quarterly over 12 months. A total of 109 incident STIs occurred (50 in the doxycycline-PEP group [25.1 per 100 person-years] and 59 in the standard-care group [29.0 per 100 person-years]), with no significant between-group difference in incidence (relative risk, 0.88; 95% confidence interval [CI], 0.60 to 1.29; P=0.51). Among the 109 incident STIs, chlamydia accounted for 85 (78.0%) (35 in the doxycycline-PEP group and 50 in the standard-care group; relative risk, 0.73; 95% CI, 0.47 to 1.13). No serious adverse events were considered by the trial investigators to be related to doxycycline, and there were no incident HIV infections. Among 50 randomly selected participants in the doxycycline-PEP group, doxycycline was detected in 58 of 200 hair samples (29.0%). All N. gonorrhoeae–positive isolates were resistant to doxycycline.
Conclusions
Among cisgender women, the incidence of STIs was not significantly lower with doxycycline PEP than with standard care. According to hair-sample analysis, the use of doxycycline PEP among those assigned to receive it was low.
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