Actively Recruiting

Phase 4
Age: 18Days - 60Days
MALE
Healthy Volunteers
ID07397403

The Efficacy of Doxycycline Post Exposure Prophylaxis for Preventing Sexually Transmitted Diseases (Gonorrhea, Chlamydia, Syphilis) Among Men Who Have Sex With Men in Bangkok, Thailand.

Led by Bangrak STIs Center · Updated on 2026-02-09

400

Participants Needed

1

Research Sites

34 weeks

Total Duration

On this page

Sponsors

B

Bangrak STIs Center

Lead Sponsor

M

Mahidol University

Collaborating Sponsor

AI-Summary

What this Trial Is About

Researchers are evaluating the effectiveness and safety of doxycycline to prevent sexually transmitted infections (STIs) such as gonorrhea, chlamydia, and syphilis among men who have sex with men (MSM) in Thailand. This Phase 4 study aims to understand if doxycycline post-exposure prophylaxis (DoxyPEP) can reduce the risk of these infections in this population. The study is sponsored by the Bangrak STIs Center and focuses on men aged 18 to 60 who are at risk for STIs. Participants will be randomly assigned to one of two groups: one group will receive DoxyPEP, which involves taking a single dose of 200 mg doxycycline within 24 to 72 hours after unprotected sex, while the other group will receive standard STI prevention without doxycycline. The study includes a treatment period of approximately 12 weeks. During the study, participants will have 2 to 3 clinic visits and 10 to 11 follow-up phone calls over about 11 weeks. Researchers will monitor adherence to doxycycline use and conduct regular testing for gonorrhea, chlamydia, and syphilis to assess the treatment's preventive effects. The primary outcome is to evaluate doxycycline's efficacy in preventing these infections within the 12-week study period.

CONDITIONS

Brief Title

The Efficacy of Doxycycline Post Exposure Prophylaxis for Preventing STIs Among MSM in Bangkok, Thailand.

Who Can Participate

Age: 18Days - 60Days
MALE
Healthy Volunteers

Eligibility Criteria

Eligible

You may qualify if you...

  • Biological male aged 18 to 60 years
  • Thai nationality
  • Able to read, communicate, and understand Thai
  • Men who have sex with men (MSM)
  • At least one of the following risk factors: condomless sex or condom failure with at least two partners in the past 3 months; diagnosis of gonorrhea, chlamydia, or syphilis within the past 6 months; or current use of HIV pre-exposure prophylaxis (PrEP)
  • Willing and able to participate in study procedures including clinic visits, doxycycline use records, and follow-up calls
  • Willing and able to provide written informed consent
Not Eligible

You will not qualify if you...

  • Allergy to tetracycline-class antibiotics
  • Untreated syphilis or currently receiving treatment with benzathine penicillin G or doxycycline
  • Receipt of benzathine penicillin G within the past 12 weeks
  • Prior receipt of a gonorrhea vaccine
  • Current use of medications that may interact with doxycycline, including vitamin A derivatives, antiepileptic drugs, immunosuppressants, heart failure or arrhythmia medications, anticoagulants, or drugs affecting blood cells
  • History of renal impairment (eGFR < 60 mL/min/1.73 m²) or hepatic impairment (AST or ALT > 3 times upper limit)
  • Uncontrolled or unstable diseases such as hematologic disorders, cancer, autoimmune, or neurological disorders
  • Severe medical or psychiatric conditions increasing study risk or impairing consent ability
  • Alcohol or illicit drug dependence within past 12 months
  • Previous participation in this study with prior randomization

AI-Screening

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Your Study Journey

Screening

Duration - 2 to 4 weeks

Participants are screened for eligibility to participate in the trial.

1 visit (in-person)

Treatment

Duration - 12 weeks

Participants receive doxycycline as post-exposure prophylaxis after unprotected sex, or standard STI prevention in the control group.

Regular visits as needed for doxycycline use and study follow-up

Trial Site Locations

Total: 1 location

1

Bangrak STIs Center

Sathorn, Bangkok, Thailand, 10120

Actively Recruiting

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Research Team

R

Rossapnorn Kittiyaowamarn, MD

K

Kittipoom Chinhiran, MD

How is the study designed?

Study Type

INTERVENTIONAL

Masking

NONE

Allocation

RANDOMIZED

Model

PARALLEL

Primary Purpose

PREVENTION

Number of Arms

2

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Published Research Related To This Trial

Doxycycline prophylaxis and meningococcal group B vaccine to prevent bacterial sexually transmitted infections in France (ANRS 174 DOXYVAC): a multicentre, open-label, randomised trial with a 2 × 2 factorial design.

Jean-Michel Molina, Beatrice Bercot, Lambert Assoumou...

https://pubmed.ncbi.nlm.nih.gov/38797183

Post-exposure prophylaxis with doxycycline to prevent sexually transmitted infections in men who have sex with men: an open-label randomised substudy of the ANRS IPERGAY trial.

Jean-Michel Molina, Isabelle Charreau, Christian Chidiac...

https://pubmed.ncbi.nlm.nih.gov/29229440

Comparison of HIV-Positive Incidence Among Transgender Women and Men Who Have Sex with Men at Stand-Alone and Mobile Voluntary Counseling and Testing Facilities in Chiang Mai Province, Thailand.

Pimwarat Nanthaprut, Natthaporn Manojai, Pongthorn Chanlearn...

https://pubmed.ncbi.nlm.nih.gov/33835852