Randomized Directly Observed Therapy Study to Interpret Clinical Trials of Doxy-PEP (DOT-Doxy-PEP)

September 2, 2026 updated by: University of California, San Francisco
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

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

48

Phase

  • Early Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • California
      • San Francisco, California, United States, 94110
        • Recruiting
        • University of California, San Francisco/San Francisco General Hospital
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

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 Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Daily Dosing
Participants will be randomized to take once daily doxycycline 200mg for six weeks.
Drug: Doxycycline Pill
200mg Dose
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.
Drug: Doxycycline Pill
200mg Dose
Active Comparator: Weekly Dosing
Participants will be randomized to take one doxycycline 200mg dose once week.
Drug: Doxycycline Pill
200mg Dose
Active Comparator: Every Other Week Dosing
Participants will be randomized to take one doxycycline 200mg dose every other week.
Drug: Doxycycline Pill
200mg Dose

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Hair Doxycycline Concentration
Time Frame: 4 weeks
Doxycycline concentrations will be measured using liquid chromatography tandem mass spectrometry within hair samples for each of the four dosing patterns within an intensive washout pharmacokinetic phase following initial dosing.
4 weeks
Plasma Doxycycline Concentration
Time Frame: 4 weeks
Doxycycline concentrations will be measured using liquid chromatography tandem mass spectrometry within plasma samples for each of the four dosing patterns within an intensive washout pharmacokinetic phase following initial dosing.
4 weeks
Urine Doxycycline Concentration
Time Frame: 4 weeks
Doxycycline concentrations will be measured using liquid chromatography tandem mass spectrometry within urine samples for each of the four dosing patterns within an intensive washout pharmacokinetic phase following initial dosing.
4 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of California, San Francisco

Collaborators

National Institute of Allergy and Infectious Diseases (NIAID)

Investigators

  • Principal Investigator: Matthew Spinelli, MD, MAS, University of California, San Francisco

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 18, 2024

Primary Completion (Estimated)

September 1, 2028

Study Completion (Estimated)

December 1, 2028

Study Registration Dates

First Submitted

May 9, 2024

First Submitted That Met QC Criteria

May 13, 2024

First Posted (Actual)

May 16, 2024

Study Record Updates

Last Update Posted (Actual)

September 4, 2026

Last Update Submitted That Met QC Criteria

September 2, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AI186641
  • R01AI186641 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Subscribe