NCT06738407

Doxycycline Prophylaxis for Prevention of Sexually Transmitted Infections

Doxycycline Prophylaxis for Prevention of Sexually Transmitted Infections Among Adolescent and Young Adult Females in the United States

• Status: Not Yet Recruiting
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 760 (estimated)
• Sponsor: Westat · Academic / Other
• Sex: Female
• Age: 13 Years – 29 Years
• Healthy volunteers: Not accepted

Summary

The goal of this open-label, randomized trial is to assess the efficacy of doxycycline prophylaxis in reducing incidences of bacterial sexually transmitted infections (STIs) among adolescent and young adult females while also evaluating acceptability and antimicrobial resistance in order to inform public health policy.

Detailed description

Participants will be randomized to receive on-demand doxycycline post-exposure prophylaxis (doxyPEP), weekly doxycycline, or standard of care (SOC) and will be followed quarterly to assess the impact of doxycycline use on the quarterly incidence of STIs (gonorrhea \[GC\], chlamydia \[CT\], and early syphilis), and within the doxycycline arms adherence and acceptability of weekly versus on-demand dosing. Approximately 760 females will be randomized 1:1:1 to (1) on-demand doxyPEP (doxycycline 200 mg as soon as possible and within 72 hours after any condomless oral, vaginal, and/or anal sex), (2) weekly doxycycline (doxycycline 200 mg weekly regardless of sexual activity), or (3) SOC (quarterly STI testing/treatment and sexual health counseling). Participants will complete quarterly study visits over the course of 1 year during which they will receive STI testing (GC, CT, and syphilis), complete surveys, undergo safety monitoring, provide specimens for objective markers of doxycycline adherence and other laboratory assessments, and provide specimens (vaginal and rectal swabs \[participant self-collected or staff-collected if the participant prefers\]) for future testing, such as microbiome analysis. Resistance testing will be conducted on Staphylococcus (S.) aureus and Neisseria (N.) gonorrhoeae isolates to evaluate for doxycycline and tetracycline resistance, respectively. Participants will also complete weekly assessments of sexual activity and doxycycline adherence via the HealthMpowerment (HMP) application (app).

Conditions

• Gonorrhea
• Chlamydia
• Syphilis
• Sexually Transmitted Infections (STIs)

Interventions

Type	Name	Description
DRUG	Doxycycline hyclate delayed released 200 mg	200 mg of doxycycline taken by mouth as soon as possible and within 72 hours after any condomless oral, vaginal, and/or anal sex along with STI screening and sexual health counseling
DRUG	Doxycycline hyclate delayed released 200 mg weekly	200 mg of doxycycline taken by mouth weekly regardless of sexual activity along with STI screening and sexual health counseling
OTHER	Per standard of care with quarterly STI testing/treatment and sexual health counseling	Quarterly STI testing/treatment and sexual health counseling

Timeline

• Start date: 2026-01-05
• Primary completion: 2028-06-15
• Completion: 2028-06-15
• First posted: 2024-12-17
• Last updated: 2026-01-02

Locations

12 sites across 1 country: United States

Regulatory

• FDA-regulated drug study