A Randomized Controlled Trial of Doxycycline Post Exposure Prophylaxis to Prevent Incident Bacterial STIs Among Women in the United States

July 10, 2026 updated by: Tulane University
The bacterial sexually transmitted infections (STIs) chlamydia, gonorrhea, and syphilis cause multiple adverse outcomes in women, and prevention strategies are critically needed. This project will determine the efficacy of doxycycline post-exposure prophylaxis (doxy PEP) to prevent STIs among women through a phase IV, open-label, randomized controlled trial.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The bacterial sexually transmitted infections (STIs) chlamydia (CT), gonorrhea, and syphilis cause multiple adverse outcomes in women, and rates of these infections have increased dramatically over the past two decades. Prevention of these infections is now possible with the use of doxycycline post-exposure prophylaxis (doxy PEP), which has demonstrated efficacy in multiple studies conducted among men from high prevalence groups. However, only one trial of the use of doxy PEP (dPEP Kenya) has been conducted among women, and unfortunately this study had a null result. Our proposed project seeks to evaluate doxy PEP efficacy among women in the United States through an open-label, randomized controlled trial (RCT) conducted in three jurisdictions (New Orleans, LA; Birmingham, AL; Chicago, IL) with high STI prevalence. Close adherence monitoring is critical given that the dPEP Kenya study's null result was likely related to poor medication adherence; thus, this trial will monitor and reinforce doxycycline adherence throughout the study using a novel PCheck app developed by our team, test urines for doxycycline levels on all participants, and hair on a nested cohort. The study's aim to conduct an RCT in 519 sexually active, non-pregnant women aged 18-35, randomizing 2:1 to better evaluate adverse events related to doxy PEP, powering the study on CT as the most commonly anticipated STI; sensitivity analyses will compare CT rates based on adherence measured by doxycycline levels in urine and by self-reported pill-taking. To execute these aims, we have assembled a multidisciplinary team with extensive expertise in the conduct of clinical trials, bioinformatics, biostatistics, infectious diseases epidemiology, STI prevention, the vaginal microbiome, behavioral health interventions, and qualitative science. MPIs Clement, Kissinger, and Muzny collectively have decades of collaborative experience enrolling priority populations in large clinical trials aimed to improve sexual health outcomes. Ultimately, this trial has the potential to have substantial public health impact, leading to a novel bacterial STI prevention intervention to reduce the undue burden of incident bacterial STIs among women.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
519

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Female
  • Aged 18-35

  • Reporting condomless vaginal sex with men AND least one of the following:

    1. diagnosis of CT, gonorrhea, syphilis, or trichomonas in the past year
    2. reporting 2 or more sexual partners in the past 6 months
  • Plan to continue to be sexually active over the next year
  • Have smartphone and be willing to engage with an app
  • If HIV+: Viral load<200 copies/ml and CD4 count >200 cells/mm3

Exclusion Criteria:

  • Pregnant, nursing, or intending to become pregnant
  • Reported allergy to tetracyclines
  • Liver disease or end-stage renal disease
  • Non-English Speaking
  • Taking concomitant medications which may impact doxycycline metabolism (e.g., systemic retinoids, antacids, barbiturates, carbamazepine, phenytoin, iron, warfarin, rifampin)
  • Not willing to take doxy PEP or comply with study procedures
  • Unable to provide informed consent

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: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Intervention
200 mg oral doxy PEP (N=346)
Drug: Doxycycline
Enrolled participants will be randomized 2:1 to receive 200 mg of doxy PEP taken within 24 hours of condomless sex versus standard of care. Only one trial of the use of doxy PEP (dPEP Kenya) has been conducted among women, and unfortunately this study had a null result.
Other Names:
  • Doxy PEP
Active Comparator: Control
Standard of care (i.e. no doxy PEP, N=173)
Other: Standard of Care (SOC)
Enrolled participants will be randomized 2:1 to receive 200 mg of doxy PEP taken within 24 hours of condomless sex versus standard of care. Only one trial of the use of doxy PEP (dPEP Kenya) has been conducted among women, and unfortunately this study had a null result.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
chlamydia incidence
Time Frame: Participants will be evaluated at baseline and quarterly for 48 weeks with STI testing at each visit.
The primary outcome will be the number of CT infections over person-time (incidence rate).
Participants will be evaluated at baseline and quarterly for 48 weeks with STI testing at each visit.

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Tulane University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute of Allergy and Infectious Diseases (NIAID)
University of Alabama at Birmingham
Louisiana State University Health Sciences Center in New Orleans

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 (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 1, 2027

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 28, 2031

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 1, 2032

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 10, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 10, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 15, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 15, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 10, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • R01AI196614

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

STI lab tests results, surveys results from baseline and quarterly visits, app data, doxycycline drug levels by urinalysis, doxycycline hair levels

IPD Sharing Access Criteria

Data will be shared in dedicated data repositories. The selected repositories will provide a persistent unique identifier for the datasets such as a Digital Object Identifier (DOI) or accession number. The unique identifiers will be included in associated publications. Dataset submission will be populated with keywords to maximize findability of the datasets. Access to the shared data will be free and unrestricted. Persons who wish to access raw data will need to send a written request to the MPIs (Drs. Kissinger, Muzny, and Clement), providing them with an explanation of the reason for the request. This request will be reviewed by the MPIs and, if deemed appropriate, submitted to the IRB of record for approval.

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.

Yes

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.

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