Comparisons of Treatment Responses of Early Syphilis to Benzathine Penicillin G With or Without Doxycycline

November 16, 2025 updated by: National Taiwan University Hospital

Comparisons of Treatment Responses of Early Syphilis to 2.4 Milliunits (MU) Single-dose Benzathine Penicillin G With or Without Doxycycline in People Living With HIV

This randomized controlled superiority study will be conducted during 2023-2025. The eligible participants are adult people living with HIV (PLWH) who are newly diagnosed with early syphilis. Participants will be randomized in a 1:1 ratio to receive single-dose benzathine penicillin G (BPG) (2.4 MU intramuscularly once) plus doxycycline (100 mg orally twice daily for 7 days) or single-dose BPG. The primary outcome is serologic response, defined as a decline of rapid plasma reagin (RPR) titer by 4-fold or greater, at week 24 and week 48; and the secondary outcomes include microbiologic response of syphilis and bacterial sexually transmitted infections (STIs) assessed by nucleic-acid amplification test (NAAT) at week 4.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

688

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Taiwan
      • Kaohsiung City, Taiwan
        • Recruiting
        • Kaohsiung Veterans General Hospital
        • Contact:
      • Kaohsiung City, Taiwan
        • Recruiting
        • Kaohsiung Medical University Chung-Ho Memorial Hospital
        • Contact:
      • Tainan, Taiwan
        • Recruiting
        • National Cheng-Kung University Hospital
        • Contact:
      • Tainan, Taiwan
        • Recruiting
        • Chi Mei Medical Hospital
        • Contact:
    • Taiwan
      • Hsinchu, Taiwan, Taiwan, 110
        • Recruiting
        • National Taiwan University Hospital Hsin-Chu Branch
        • Contact:
      • Taipei, Taiwan, Taiwan, 110
        • Recruiting
        • Far Eastern Memorial Hospital
        • Contact:
        • Contact:
          • Kuan-Yin Lin
      • Taipei, Taiwan, Taiwan, 110
        • Recruiting
        • National Taiwan University Hospital
        • Contact:
      • Taipei, Taiwan, Taiwan, 110
        • Recruiting
        • Taipei Vetetrans General Hospital
        • Contact:
      • Taoyuan District, Taiwan, Taiwan, 110
        • Recruiting
        • TaoYuan General Hospital
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • People living with HIV (PLWH) aged ≥18 years with early syphilis
  • Confirmed by a positive RPR titer with a reactive TPPA assay

Exclusion Criteria:

  • PWH with RPR titers of <4
  • Exposure to antibiotics with activity against T. pallidum within the preceding 4 weeks (penicillin, 3rd cephalosporin, doxycycline, macrolides)
  • A known or suspected infection requiring additional treatment with an antimicrobial active against T. pallidum (penicillin, 3rd cephalosporin, doxycycline, macrolides)
  • Testing positive for C. trachomatis and M. genitalium, for which doxycycline or macrolide was administered
  • A history of intolerance to penicillin or doxycycline
  • PLWH have already participated in this study
  • Pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: single-dose BPG plus doxycycline
single-dose benzathine penicillin G (2.4 MU intramuscularly once) plus doxycycline (100 mg orally twice daily for 7 days)
Drug: Benzathine Penicillin G
Benzathine Penicillin G (2.4 MU intramuscularly once)
Drug: Doxycycline Capsule
doxycycline (100 mg orally twice daily for 7 days)
Placebo Comparator: single-dose BPG
single-dose benzathine penicillin G (2.4 MU intramuscularly once)
Drug: Benzathine Penicillin G
Benzathine Penicillin G (2.4 MU intramuscularly once)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Serologic response
Time Frame: Weeks 24 and week 48
Either a 4-fold or greater decline in RPR titer compared to baseline or being RPR-nonreactive
Weeks 24 and week 48

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Microbiologic response of syphilis
Time Frame: Week 4
T. pallidum PCR Ct value >38
Week 4
Microbiologic response of bacterial STIs
Time Frame: Week 4
negative STI PCR results
Week 4
Safety of study treatment
Time Frame: Week 4
Week 4
Adherence evaluation of tablet intake
Time Frame: Week 4
Week 4

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Taiwan University Hospital

Collaborators

Kaohsiung Medical University Chung-Ho Memorial Hospital
Taipei Veterans General Hospital, Taiwan
National Cheng-Kung University Hospital
Far Eastern Memorial Hospital
Kaohsiung Veterans General Hospital.
Chi Mei Medical Hospital
National Taiwan University Hospital Hsin-Chu Branch
Taoyuan General Hospital

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 1, 2024

Primary Completion (Estimated)

December 31, 2027

Study Completion (Estimated)

December 31, 2028

Study Registration Dates

First Submitted

October 1, 2023

First Submitted That Met QC Criteria

October 1, 2023

First Posted (Actual)

October 5, 2023

Study Record Updates

Last Update Posted (Actual)

November 18, 2025

Last Update Submitted That Met QC Criteria

November 16, 2025

Last Verified

October 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 202305061MINA

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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