Recruiting
Early Phase 1

Doxy-PEP

Sponsor:

UCLA

Code:

NCT06414408

Conditions

Sexually Transmitted Diseases, Bacterial

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Interventions

Doxycycline Pill

Study Details

Brief summary:

Rates of bacterial sexually transmitted infections (STIs) are rising globally, demanding innovative interventions beyond the scope of current efforts to prevent STIs. The United States Doxycycline Post-exposure Prophylaxis (DoxyPEP) Study has demonstrated the efficacy of doxycycline post-exposure prophylaxis (PEP) among men who have sex with men and transgender women; but puzzlingly, doxycycline PEP was found ineffective in cisgender women in the Kenyan doxycycline Post-Exposure Prophylaxis (dPEP) study, with preliminary data suggesting the low medication adherence may explain the null result. By study end, the investigators will have developed adherence measurement methods for doxycycline in hair, blood, and urine, and will use these techniques to help interpret the Kenyan dPEP study, and to examine the relative performance of these methods within the United States DoxyPEP trial, establishing adherence metrics for current and future rollout studies of doxycycline post-exposure prophylaxis

Conditions

Sexually Transmitted Diseases, Bacterial

Study ID

NCT06414408

Start date

Oct 18, 2024

Status verified date

Sep, 2026

Completion date

Dec 1, 2028

Anticipated

Primary completion date

Sep 1, 2028

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Inclusion Criteria:

  • not currently at risk of a sexually transmitted infection and willing to use other methods, such as condoms, for STI prevention;
  • if diagnosed with an STI in the past two years and/or a partner was diagnosed with an STI in the past year, is willing to use condoms for STI prevention;
  • willing to provide hair, blood, and urine samples;
  • not currently enrolled in other STI prevention studies;
  • able to speak English
  • transgender women participants should be currently using estrogen gender affirming hormone therapy with blood estrogen levels demonstrating consistent use
  • transgender men participants should be currently using testosterone gender affirming hormone therapy with blood testosterone levels demonstrating consistent use
  • able to provide a hair sample of \~50-100 strands of hair that are non-gray, not bleached, and at least 1cm in length
  • willing to NOT shave hair or have a very short haircut or apply bleach for the duration of the study
  • has suitable venous access for consecutive blood draws

Exclusion Criteria:

  • any health condition that may interfere with participation or the ability to provide informed consent, including any debilitating or life-threatening conditions;
  • pregnancy or plans to become pregnant;
  • liver cirrhosis or fulminant liver disease;
  • known hypersensitivity reaction to doxycycline.
  • detectable doxycycline in hair at enrollment.
  • unable to provide a hair sample of \~50-100 strands of hair that are non-gray, not bleached, and at least 1cm in length
  • does not have suitable venous access for consecutive blood draws

Study Design

Enrollment

48 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

active comparator: Daily Dosing

Participants will be randomized to take once daily doxycycline 200mg for six weeks.

active comparator: Three-times Weekly Dosing

Participants will be randomized to take one doxycycline 200mg dose three times a week (Monday, Wednesday, and Friday) for six weeks.

active comparator: Weekly Dosing

Participants will be randomized to take one doxycycline 200mg dose once week.

active comparator: Every Other Week Dosing

Participants will be randomized to take one doxycycline 200mg dose every other week.

Interventions

Doxycycline Pill

200mg Dose

Primary outcome measure

  • Hair Doxycycline Concentration [ Time Frame: 4 weeks ]
  • Plasma Doxycycline Concentration [ Time Frame: 4 weeks ]
  • Urine Doxycycline Concentration [ Time Frame: 4 weeks ]

Central Contacts and Locations

Central contacts

Shivani Mahuvakar

415-878-6384DOTDoxyPEP@ucsf.edu

Locations

University of California, San Francisco/San Francisco General Hospital

Recruiting

San Francisco, California, United States, 94110

Contacts

Matthew A Spinelli, MD, MAS

matthew.spinelli@ucsf.edu

More Information

Sponsor

University of California, San Francisco

Last update posted

Sep 4, 2026

Last verified

Sep, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of California, San Francisco on 2026-09-04.