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Chlamydial InfectionPhase 4NCT05840159

A Study of Doxycycline to Treat Chlamydial Infection

A Phase 4 study testing Doxycycline in people with Chlamydial Infection, run by National Institute of Allergy and Infectious Diseases (NIAID) at 7 sites in 2 countries.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial 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). Read more about this study

Who is it for?
Ages 16 years and older
Conditions the study is for
Chlamydial Infection
What is being tested?
Doxycycline
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
526 participants
Where
7 sitesin 2 countries
Study dates
19 Jan 2024to 12 Feb 2026
Phase
Phase 4
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 16 years and older
  • All sexes
  • No healthy volunteers
  • Child, Adult, Older adult

Who may be able to join

  • 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

Who cannot join

  • 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.
  • Received antimicrobial therapy active against C. trachomatis within 21 days prior to positive chlamydia (CT) test result, or between the positive chlamydia (CT) test result and study enrollment Use of the following antibiotics is exclusionary: doxycycline and related tetra- or glycylcyclines, macrolides (including azithromycin), fluoroquinolones, rifampin, quinupristin-dalfopristin, and linezolid. Note: Amoxicillin, penicillin, ceftriaxone, and other beta-lactam antibiotics are not considered exclusionary for this study.
  • 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
Show all 17Show fewer
  • 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
  • Diagnosis of HIV

Trial locations and contacts

7 sites in 2 countries.

7 sites in 2 countries

United States5 sites
  • Grady Memorial Hospital

    Atlanta, Georgia, 30303

  • Emory University Hospital Midtown - Emory Clinic Infectious Diseases

    Atlanta, Georgia, 30308

  • University of Alabama at Birmingham School of Medicine - Infectious Disease

    Birmingham, Alabama, 35222

  • University of Rochester Medical Center - Vaccine Research Unit

    Rochester, New York, 14642-0001

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

    Seattle, Washington, 98104-2433

Other trials in United States

Kenya2 sites
  • Pwani Research Centre

    Mombasa

  • KEMRI-CCR PHRD Project

    Thika

Other trials in Kenya

About this study

Official title: A Phase 4 Study of a 3-Day vs. 7-Day Regimen of Doxycycline for the Treatment of Chlamydial Infection

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).

Read the detailed description

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).

The primary objective is to compare the efficacy of a 3-day vs. 7-day regimen of doxycycline for treatment of urogenital chlamydia (CT) infection in women based on proportion of participants with microbiologic cure (negative nucleic acid amplification test [NAAT] of vaginal swab and no positive nucleic acid amplification test (NAAT) of vaginal swab between study treatment and Day 29) at Day 29. Also, to compare the efficacy of a 3-day vs. 7-day regimen of doxycycline for treatment of rectal chlamydia (CT) infection in men based on proportion of participants with microbiologic cure (negative nucleic acid amplification test (NAAT) of rectal swab and no positive nucleic acid amplification test (NAAT) of rectal swab between study treatment and Day 29) at Day 29. The secondary objectives are to compare the efficacy of a 3-day vs. 7-day regimen of doxycycline for treatment of rectal CT infection in women based on microbiologic cure. Also, to compare the efficacy of a 3-day vs. 7-day regimen of doxycycline for treatment of urethral CT infection in men based on microbiologic cure. In addition, compare the efficacy of a 3-day vs. 7-day regimen of doxycycline for treatment of total CT infection (any anatomic site) in women and men based on microbiologic cure. Lastly, to compare the efficacy of a 3-day vs. 7-day regimen of doxycycline for treatment of rectal CT infection in men based on microbiologic cure, stratified by lymphogranuloma venereum (LGV) status.

Being tested
Doxycycline, Placebo
Keywords
Chlamydia, Doxycycline, Infection, intervention, Phase 4
Medical subject headings
Chlamydia Infections, Infections

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • DoxycyclineDrug

    Doxycycline is a synthetic tetracycline derivative with similar antimicrobial activity.

  • PlaceboOther

    Placebo

Study groups in NCT05840159
Study groupRoleWhat they receive
Arm 1Experimental100 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.
Receives: Drug: Doxycycline; Other: Placebo
Arm 2Active comparator100 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.
Receives: Drug: Doxycycline
Arm 3Experimental100 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.
Receives: Drug: Doxycycline; Other: Placebo
Arm 4Active comparator100 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.
Receives: Drug: Doxycycline

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. 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

    Measured: Day 1 through Day 29

  2. 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.

    Measured: Day1 through Day 29

Secondary outcomes (6)
  1. Proportion of assigned men participants with microbiologic cure as detected via urine

    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.

    Measured: Day 1 through Day 29

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

    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.

    Measured: Day 1 through Day 29

  3. Proportion of assigned women 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.

    Measured: Day 1 through Day 29

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

    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.

    Measured: Day1 through Day 29

  5. Proportion of lymphogranuloma venereum (LGV)-negative 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.

    Measured: Day 1 through Day 29

  6. Proportion of lymphogranuloma venereum (LGV)-positive 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.

    Measured: Day 1 through Day 29

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted3 May 2023
  2. Study start19 Jan 2024
  3. Primary completion12 Feb 2026
  4. Study completion12 Feb 2026

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 4
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
Triple blind
Who is masked
Participant, Care provider, Investigator
Enrolment
526 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05840159
Sponsor's protocol ID
22-0019
Other IDs
5UM1AI148684-03
Status last verified
22 Apr 2025
First submitted
21 Apr 2023
Last updated
27 Mar 2026
Results posted
No
FDA-regulated drug
Yes
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 4 study testing Doxycycline in people with Chlamydial Infection, run by National Institute of Allergy and Infectious Diseases (NIAID) at 7 sites in 2 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 8 inclusion and 17 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 27 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 7 sites in United States, Kenya. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Proportion of assigned men participants with microbiologic cure as detected via rectal swab (time frame: Day 1 through Day 29). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 27 Mar 2026.

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