Superiority of On-demand PrEP Versus PEP on Using Doxycycline for Preventing STI in MSM

NCT06188442 | Recruiting Phase 4 DMC

• 1 other identifier: 23220262
• Study Type: interventional
• Target: 300
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to compare the effectiveness of doxycycline taken for on-demand pre-exposure prophylaxis (DoxyODPrEP) and its post-exposure use (DoxyPEP) in preventing bacterial sexually transmitted infections (STI), including chlamydia, gonorrhoea, and syphilis among men who have sex with men (MSM). The main questions it aims to answer are:

1. 1.Is DoxyODPrEP superior to DoxyPEP?
2. 2.Are both regimens safe?
3. 3.Does the MSM community accept the use of doxycycline to prevent bacterial STI?

Conditions

Sexually Transmitted Diseases, Bacterial; Syphilis; Gonorrhea; Chlamydia

Keywords

doxycycline; men who have sex with men; sexually transmitted infections

Outcome Measures

Primary Outcomes (3)

• Time to the first episode of gonorrhoea after the enrolment visit

  Time to the first episode of gonorrhoea after the enrolment visit

  Months 1 to 24

• Time to the first episode of chlamydia after the enrolment visit

  Time to the first episode of chlamydia after the enrolment visit

  Months 1 to 24

• Time to the first episode of syphilis after the enrolment visit

  Time to the first episode of syphilis after the enrolment visit

  Months 1 to 24

Secondary Outcomes (4)

• Safety profile

  Months 1 to 24

• Acceptability of regimens

  Months 1 to 24

• Retention

  Months 1 to 24

• Time to the first episode of HIV after the enrolment visit

  Months 1 to 24

Study Arms (2)

DoxyODPrEP

ACTIVE COMPARATOR

Participants in the DoxyODPrEP arm would be instructed to take two doxycycline hyclate 100mg capsules orally 2-24 hours before sex, and one 100mg capsule each 24 and 48 hours after loading dose. If they have sex within 48 hours after the loading dose, they would be asked to continue a daily 100mg until two days after the last sex.

Drug: DoxyODPrEP

DoxyPEP

ACTIVE COMPARATOR

Participants in the DoxyPEP arm would be instructed to take two doxycycline hyclate 100mg capsules orally within 24 hours and up to 72 hours after each sex.

Drug: DoxyPEP

Interventions

DoxyODPrEP DRUG

Participants in the DoxyODPrEP arm would be instructed to take two doxycycline hyclate 100mg capsules orally 2-24 hours before sex, and one 100mg capsule each 24 and 48 hours after loading dose. If they have sex within 48 hours after the loading dose, they would be asked to continue a daily 100mg until two days after the last sex

Also known as: doxycycline on demand PrEP

DoxyODPrEP

DoxyPEP DRUG

Participants in the DoxyPEP arm would be instructed to take two doxycycline hyclate 100mg capsules orally within 24 hours and up to 72 hours after each sex.

Also known as: doxycycline PEP

DoxyPEP

Eligibility Criteria

• Age: 18 Years+
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• has had sex with another male in the past six months
• normally reside in Hong Kong
• can communicate in written and spoken Chinese or English
• willing and able to give written informed consent
• being willing and able to attend scheduled study clinic visits
• at risk of STI (had condomless sex with more than one man in the past 12 months, history of STI diagnosis in the past 12 months, inclination to have condomless sex, and other HIV-PrEP-eligible criteria)

You may not qualify if:

• Being allergic to tetracycline class medicines
• Currently taking medications that are contraindicated with doxycycline
• Using antibiotics for more than 14 days in the month preceding enrolment

Sponsors & Collaborators

• Chinese University of Hong Kong: lead

Study Sites (1)

Stanley Ho Centre for Emerging Infectious Diseases

Shatin, Hong Kong

RECRUITING

MeSH Terms

Conditions

Sexually Transmitted Diseases, Bacterial; Syphilis; Gonorrhea; Chlamydia Infections; Homosexuality; Sexually Transmitted Diseases

Condition Hierarchy (Ancestors)

Bacterial Infections; Bacterial Infections and Mycoses; Infections; Communicable Diseases; Genital Diseases; Urogenital Diseases; Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Treponemal Infections; Spirochaetales Infections; Gram-Negative Bacterial Infections; Neisseriaceae Infections; Chlamydiaceae Infections; Sexuality; Sexual Behavior; Behavior

Study Officials

• Tsz Ho Kwan, PhD

  Jockey Club School of Public Health and Primary Care

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Secretariat

CONTACT

22528812; ceid@med.cuhk.edu.hk

Tsz Ho Kwan, PhD

CONTACT

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Research Assistant Professor

Model Details: With a 3:1 intervention-to-control allocation ratio (198 and 66 participants would receive intervention and control, respectively), a total of 264 participants would be recruited.

Study Record Dates

• First Submitted: December 18, 2023
• First Posted: January 3, 2024
• Study Start: March 29, 2025
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 1, 2028
• Last Updated: April 4, 2025

Record last verified: 2025-04

Locations

HK (1)