A Study of Doxycycline to Treat Chlamydial Infection

NCT05840159 | Completed Phase 4 FDA Drug

• 2 other identifiers: 22-00195UM1AI148684-03
• Study Type: interventional
• Target: 526
• Locations: 2 countries
• Sites: 7

Brief Summary

This is a Phase 4 blinded, randomized, active-controlled, non-inferiority trial. Final evaluable population will include a minimum 596 individuals: 298 women with confirmed urogenital chlamydia (CT) and 298 men with confirmed rectal chlamydia (CT). Approximately 664 participants will be enrolled to achieve a minimum 596 participants who contribute primary outcome data. Randomization will be stratified by study site and sex: 332 women and 332 men. Participants will be randomized 1:1 to a 3-day regimen of doxycycline or a 7-day regimen of doxycycline. The study blind will be maintained by providing 7 days of identical pre-filled blister packs, one with 3 days of active treatment and 4 days of placebo, and the other with 7 days of active treatment. Participants will be asked to return 28 days after randomization (at day 29), at which time they will be re-tested for chlamydia (CT) using a laboratory-based chlamydia (CT) nucleic acid amplification test (NAAT).

Conditions

Chlamydial Infection

Keywords

Chlamydia; Doxycycline; Infection; intervention; Phase 4

Outcome Measures

Primary Outcomes (2)

• Proportion of assigned men participants with microbiologic cure as detected via rectal swab

  A participant with microbiologic cure is defined as having a negative Chlamydia trachomatis (CT) Nucleic Acid Amplification Test (NAAT) at Day 29 and no positive CT NAATs between study treatment and Day 29

  Day 1 through Day 29

• Proportion of assigned women participants with microbiologic cure as detected via vaginal swab

  A participant with microbiologic cure is defined as having a negative Chlamydia trachomatis (CT) Nucleic Acid Amplification Test (NAAT) at Day 29 and no positive CT NAATs between study treatment and Day 29.

  Day1 through Day 29

Secondary Outcomes (6)

• Proportion of assigned men participants with microbiologic cure as detected via urine

  Day 1 through Day 29

• Proportion of assigned men participants with microbiologic cure at all anatomic sites that were positive at baseline

  Day 1 through Day 29

• Proportion of assigned women participants with microbiologic cure as detected via rectal swab

  Day 1 through Day 29

• Proportion of assigned women participants with microbiologic cure at all anatomic sites that were positive at baseline

  Day1 through Day 29

• Proportion of lymphogranuloma venereum (LGV)-negative assigned men participants with microbiologic cure as detected via rectal swab.

  Day 1 through Day 29

Study Arms (4)

Arm 1

EXPERIMENTAL

100 mg of doxycycline orally administered twice daily for 3 days and 4 days of placebo to assigned women participants \>/= 16 years old with confirmed urogenital Chlamydia trachomatis (CT). N=166.

Drug: Doxycycline; Other: Placebo

Arm 2

ACTIVE COMPARATOR

100 mg of doxycycline orally administered twice daily for 7 days to assigned women participants \>/= 16 years old with confirmed urogenital Chlamydia trachomatis (CT). N=166.

Drug: Doxycycline

Arm 3

EXPERIMENTAL

100 mg of doxycycline orally administered twice daily for 3 and 4 days of placebo days to assigned men participants \>/= 16 years old with confirmed rectal Chlamydia trachomatis (CT). N=166.

Drug: Doxycycline; Other: Placebo

Arm 4

ACTIVE COMPARATOR

100 mg of doxycycline orally administered twice daily for 7 days to assigned men participants \>/= 16 years old with confirmed rectal Chlamydia trachomatis (CT). N=166.

Drug: Doxycycline

Interventions

Doxycycline DRUG

Doxycycline is a synthetic tetracycline derivative with similar antimicrobial activity.

Arm 1; Arm 2; Arm 3; Arm 4

Placebo OTHER

Placebo

Arm 1; Arm 3

Eligibility Criteria

• Age: 16 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• Has untreated urogenital chlamydia (CT) (in women) or rectal CT (in men), diagnosed with a positive nucleic acid amplification test (NAAT) (point-of care or laboratory-based)\* result within 14 days
• \*Point-of-care (POC) test may or may not be FDA-cleared for CLIA waiver for diagnosis depending upon anatomic site of infection.
• Must be age \>/=16 years (where the IRB permits individuals aged 16-17 years old to consent to research); otherwise age \>/= 18 years
• Willing and able to understand and provide written informed consent before initiation of any study procedures
• Willing to complete a 7-day study drug regimen
• Willing to abstain from condomless anal or vaginal sex during the trial
• Willing and able to adhere to planned study procedures for all study visits
• Has valid contact information

You may not qualify if:

• For women: lower abdominal or pelvic pain or other signs or symptoms consistent with a clinical diagnosis of pelvic inflammatory disease (PID) Per the CDC's 2021 STD Treatment Guidelines or refer to local guidelines.
• Signs and symptoms that, in the judgement of a qualified clinician, warrant a prolonged course of treatment with doxycycline For example, 21 days of doxycycline for presumed lymphogranuloma venereum infection.
• Planning to take antimicrobial therapy active against chlamydia (CT) during the study period (e.g. doxycycline post-exposure prophylaxis, treatment for Mycoplasma genitalium infection, acne, or any other non-STI medical condition).
• Currently enrolled in or plan to enroll in another study using antimicrobial therapy active against C. trachomatis during the study period
• Pregnant or lactating, or plan to become pregnant within the study period
• Known moderate to severe allergy to tetracyclines, excluding tetracycline-induced photosensitivity.
• Plan to move or travel to another location that would preclude study follow-up appointments in clinic in the next 30 days
• Use of a medication contraindicated to treatment with doxycycline within 7 days prior to enrollment or during the study period (systemic retinoids, barbiturates, carbamazepine, phenytoin, warfarin)
• Previous enrollment in this trial
• Any condition that, in the judgment of the investigator, precludes participation because it could affect participant safety or determination of study endpoints.
• Of note, the following factors will NOT exclude participants from the study:
• Concomitant untreated gonorrhea (rectal, pharyngeal, or urethral) or known exposure to gonorrhea in the time between CT testing and study enrollment. Gonococcus (GC) infection identified during the course of pre-screening or screening will be treated per clinic standard practice and in accordance with local guidelines without concomitant azithromycin or other treatment for Chlamydia trachomatis infection.
• Clinical diagnosis of concomitant untreated primary or secondary syphilis or known exposure to syphilis
• Urethritis among men
• Contraception status

Sponsors & Collaborators

• National Institute of Allergy and Infectious Diseases (NIAID): lead

Study Sites (7)

University of Alabama at Birmingham School of Medicine - Infectious Disease

Birmingham, Alabama, 35222, United States

Location

Grady Memorial Hospital

Atlanta, Georgia, 30303, United States

Location

Emory University Hospital Midtown - Emory Clinic Infectious Diseases

Atlanta, Georgia, 30308, United States

Location

University of Rochester Medical Center - Vaccine Research Unit

Rochester, New York, 14642-0001, United States

Location

University of Washington - Harborview Medical Center - Center for AIDS and STD

Seattle, Washington, 98104-2433, United States

Location

Pwani Research Centre

Mombasa, Kenya

Location

KEMRI-CCR PHRD Project

Thika, Kenya

Location

MeSH Terms

Conditions

Chlamydia Infections; Infections

Interventions

Doxycycline

Condition Hierarchy (Ancestors)

Chlamydiaceae Infections; Gram-Negative Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Sexually Transmitted Diseases, Bacterial; Sexually Transmitted Diseases; Communicable Diseases; Genital Diseases; Urogenital Diseases

Intervention Hierarchy (Ancestors)

Tetracyclines; Naphthacenes; Polycyclic Aromatic Hydrocarbons; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals; Polycyclic Compounds

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: NIH
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 21, 2023
• First Posted: May 3, 2023
• Study Start: January 19, 2024
• Primary Completion: February 12, 2026
• Study Completion: February 12, 2026
• Last Updated: March 27, 2026

Record last verified: 2025-04-22

Locations

KE (2); US (5)