NCT06683638 Daily Doxycycline for Early Syphillis
| NCT ID | NCT06683638 |
| Status | Recruiting |
| Phase | Phase 2 |
| Sponsor | University of Washington |
| Condition | Syphilis |
| Study Type | INTERVENTIONAL |
| Enrollment | 15 participants |
| Start Date | 2025-03-03 |
| Primary Completion | 2026-06-26 |
Eligibility & Interventions
Eligibility Fast-Check
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What to Expect as a Participant
You will actively receive the study intervention — which may be a drug, biologic, device, or procedure.
In Phase 2, researchers evaluate early signs of effectiveness. You may be randomized to receive the active treatment or a comparator. Monitoring continues closely.
This trial targets 15 participants in total. It began in 2025-03-03 with a primary completion date of 2026-06-26.
⚠ This information is for research awareness only. Always consult your physician before joining any clinical trial. Participation is voluntary and you may withdraw at any time.
Brief Summary
The goal of this clinical trial is to learn if doxycycline taken as 200mg daily for 14 days is effective to treat early stage syphilis. This is different from how doxycycline is typically used for syphilis because the full doxycycline dose will be taken at the same time of day, rather than split up into a twice daily regimen. Lab data support that taking the medication as a single daily dose should be effective as treatment, but it has not been studied clinically. The main question this study aims to answer is: Is doxycycline taken as a single daily dose of 200mg for 14 days an effective treatment for early syphilis based on a combined outcome of clinical improvement and blood test improvement? Participants will: 1. Take doxycycline 200mg daily for 14 days 2. Submit oral and rectal swabs that test for syphilis bacteria every other day for 2 weeks, returned by mail 3. Complete 2 brief online surveys over the first 2 weeks 4. Return to the clinic for an interview and blood draw every 3 months for a maximum of 3 study visits, including the first visit The investigators will compare the percentage of participants in the study who have response to treatment by 6 months to that of persons who have received standard (CDC-recommended) regimens. To do this, the investigators will calculate response percentage estimates following a shot of long-acting penicillin or 14 days of doxycycline 100mg twice daily from 60-person samples from the sexual health program's records.
Eligibility Criteria
Inclusion Criteria: Clinical diagnosis of syphilis (primary or secondary) or laboratory-confirmed early latent syphilis. Specifically: This will include persons meeting any one of the following criteria: 1. Clinical diagnosis of primary syphilis (based on the presence of a chancre) and either a positive qualitative RPR in the absence of a prior positive RPR on their most recent serological test for syphilis or a positive darkfield microscope exam of material taken from a chancre, OR 2. Clinical diagnosis of secondary syphilis with a positive qualitative RPR in the absence of a prior positive RPR on their most recent serological test for syphilis, OR 3. A laboratory-confirmed diagnosis of early latent syphilis within one month (i.e. \<31 days prior). Exclusion Criteria: 1. age under 18 2. persons with evidence of neurosyphilis (including ocular and otic syphilis) or tertiary syphilis 3. persons who are unable to give informed consent 4. persons deemed by the study investigators to be unable to complete study follow-up visits 5. persons with an allergy to doxycycline 6. pregnant persons 7. persons with HIV who report that they are off antiretroviral medication or that they are not virologically suppressed 8. persons with other known forms of immunosuppression (e.g., persons taking systemic immunosuppressant drugs, persons with primary immunodeficiencies) 9. persons taking medications that would interact with doxycycline 10. persons whose initial RPR is lower than 1:4 11. persons currently prescribed doxy PEP 12. breastfeeding persons Persons whose initial laboratory serological tests do not confirm the diagnosis of syphilis with an RPR of 1:4 or higher will be informed that they do not meet study criteria and advised to discontinue doxycycline 200mg once daily. Their subsequent treatment will be based on the judgement of non-research, clinical staff in the clinic and reflect shared decision making between clinical providers and their patient.
Contact & Investigator
Travis Hunt, MD
PRINCIPAL INVESTIGATOR
University of Washington
Frequently Asked Questions
Who can join the NCT06683638 clinical trial?
This trial is open to participants of all sexes, aged 18 Years or older, studying Syphilis. Full inclusion and exclusion criteria are listed in the Eligibility Criteria section. Always confirm your eligibility with the research team before applying.
What phase is the NCT06683638 trial and what does that mean for participants?
Phase 2 trials evaluate whether the treatment shows signs of effectiveness while continuing to monitor safety. More participants are enrolled than in Phase 1 to help refine the treatment protocol.
Is NCT06683638 currently recruiting?
Yes, NCT06683638 is actively recruiting participants. Contact the research team at thunt91@uw.edu for enrollment information.
Where is the NCT06683638 trial being conducted?
This trial is being conducted at Seattle, United States.
Who is sponsoring the NCT06683638 clinical trial?
NCT06683638 is sponsored by University of Washington. The principal investigator is Travis Hunt, MD at University of Washington. The trial plans to enroll 15 participants.