Doxycycline Prophylaxis for Prevention of Sexually Transmitted Infections

NCT ID: NCT06738407

Last Updated: 2026-01-02

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

NOT_YET_RECRUITING

Clinical Phase

PHASE4

Total Enrollment

760 participants

Study Classification

INTERVENTIONAL

Study Start Date

2026-01-05

Study Completion Date

2028-06-15

Brief Summary

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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

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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

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Gonorrhea Chlamydia Syphilis Sexually Transmitted Infections (STIs)

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Participants 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.
Primary Study Purpose

PREVENTION

Blinding Strategy

NONE

Study Groups

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On-demand doxyPEP

Participants will take by mouth doxycycline 200 mg as soon as possible and within 72 hours after any condomless oral, vaginal, and/or anal sex in addition to standard of care STI testing/treatment and sexual health counseling.

Group Type EXPERIMENTAL

Doxycycline hyclate delayed released 200 mg

Intervention Type DRUG

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

Weekly doxycycline

Participants will take by mouth doxycycline 200 mg weekly regardless of sexual activity in addition to standard of care STI testing/treatment and sexual health counseling.

Group Type EXPERIMENTAL

Doxycycline hyclate delayed released 200 mg weekly

Intervention Type DRUG

200 mg of doxycycline taken by mouth weekly regardless of sexual activity along with STI screening and sexual health counseling

Quarterly STI testing/treatment and sexual health counseling

Participants will be followed per standard of care with quarterly STI testing/treatment and sexual health counseling.

Group Type OTHER

Per standard of care with quarterly STI testing/treatment and sexual health counseling

Intervention Type OTHER

Quarterly STI testing/treatment and sexual health counseling

Interventions

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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

Intervention Type 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

Intervention Type DRUG

Per standard of care with quarterly STI testing/treatment and sexual health counseling

Quarterly STI testing/treatment and sexual health counseling

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Age 13-29 years, inclusive;
* Self-reports GC, CT, and/or early syphilis diagnosis in the 12 months prior to screening;
* Self-reports condomless (oral, vaginal, and/or anal) intercourse at least once in the 30 days prior to screening
* Is at least 45 kilograms (99.2 pounds) in weight
* Fluent in English (able to read, speak, and understand English);
* Willing to undergo all required study procedures; and
* Willing to provide written informed consent to participate in the study.

Exclusion Criteria

* Is male;
* Is pregnant, breastfeeding, or planning to become pregnant in the next 12 months;
* Documented history of tetracycline allergy or self-reports an allergy to tetracyclines;
* Current or anticipated use of a medication (e.g., barbiturates, phenytoin, lithium, carbamazepine, systemic retinoids, warfarin) with a contraindicated interaction to doxycycline ;
* Current or planned use of doxycycline for a prolonged period (\> 2 weeks) in the 30 days prior to enrollment, including current prescription for doxycycline for STI prophylaxis;
* Prolonged antibiotic use (\> 2 weeks) within the last 30 days prior to enrollment;
* Co-enrollment in any other concurrent interventional research or studies that may interfere with this study, such as an STI prevention trial, unless approved by Protocol Team in writing;
* Does not have consistent access (or anticipated weekly access for 52 weeks of survey completion) to smartphone that can access the HMP app; or
* Any other medical condition, medical/behavioral intervention, or other conditions that, in the opinion of the clinical site Project Lead (PL)/Investigator of Record (IoR) or designee, could interfere with adherence to study procedures or compromise interpretation of study results.
Minimum Eligible Age

13 Years

Maximum Eligible Age

29 Years

Eligible Sex

FEMALE

Accepts Healthy Volunteers

No

Sponsors

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Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

NIH

Sponsor Role collaborator

National Institute of Allergy and Infectious Diseases (NIAID)/Division of AIDS (DAIDS)

UNKNOWN

Sponsor Role collaborator

National Institute on Drug Abuse (NIDA)

NIH

Sponsor Role collaborator

National Institute of Mental Health (NIMH)

NIH

Sponsor Role collaborator

Florida State University

OTHER

Sponsor Role collaborator

National Institute of Allergy and Infectious Diseases (NIAID)

NIH

Sponsor Role collaborator

The Office of the Director, National Institutes of Health (NIH)

UNKNOWN

Sponsor Role collaborator

Westat

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Cherie Blaire, MD, PhD

Role: STUDY_CHAIR

University of California, Los Angeles

Jenell Stewart, DO, MPH

Role: STUDY_CHAIR

Hennepin Healthcare

Locations

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UCLA Care

Los Angeles, California, United States

Site Status

San Francisco Department of Public Health

San Francisco, California, United States

Site Status

Children's National Medical Center

Washington D.C., District of Columbia, United States

Site Status

University of Florida

Tampa, Florida, United States

Site Status

Ponce de Leon

Atlanta, Georgia, United States

Site Status

University Illinois Chicago

Chicago, Illinois, United States

Site Status

Tulane University

New Orleans, Louisiana, United States

Site Status

Harlem Prevention Center

New York, New York, United States

Site Status

Chapel Hill

Chapel Hill, North Carolina, United States

Site Status

Penn Prevention

Philadelphia, Pennsylvania, United States

Site Status

St. Jude Children's Research Hospital

Memphis, Tennessee, United States

Site Status

Baylor College of Medicine

Houston, Texas, United States

Site Status

Countries

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United States

Central Contacts

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Nancy Liu

Role: CONTACT

718-980-3937

Erin Ricketts

Role: CONTACT

240-453-2786

Facility Contacts

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Emy Arango

Role: primary

310-825-6413

Emily Schaeffer

Role: primary

628-217-7456

Justin Unternaher

Role: primary

202-476-1030

Elizabeth Enriquez-Bruce

Role: primary

813-250-2574

Christin Root

Role: primary

404-251-8893

Rachel Jackson

Role: primary

312-996-6018

Leslie Kozina

Role: primary

504-988-5348

Yan Rivera

Role: primary

917-846-9907

Mariam Chicurel-Bayard

Role: primary

919-843-9922

Rosemarie Kappes

Role: primary

267-229-2972

Mary Dillard

Role: primary

901-595-4083

Litty Koshy

Role: primary

832-822-1038

Other Identifiers

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UM2HD111076

Identifier Type: NIH

Identifier Source: secondary_id

View Link

UM2HD111102

Identifier Type: NIH

Identifier Source: secondary_id

View Link

ATN173/HPTN 115

Identifier Type: -

Identifier Source: org_study_id

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