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Daily Doxycycline for Early Syphillis
NCT06683638 · View on ClinicalTrials.gov ↗
Study 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.
Conditions Studied
Interventions
- DRUG Doxycycline 200mg daily for 14 days
Study Locations (1)
Washington
- Public Health Sexual Health Clinic — Seattle
Trial Details
| Field | Value |
|---|---|
| Enrollment Target | 15 participants |
| Start Date | 2025-03-03 |
| Est. Completion | 2026-06-26 |
| Phase | Phase 2 |
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Full Details on ClinicalTrials.gov ↗What the Registry Record Tells You About NCT06683638
The ClinicalTrials.gov registry entry for NCT06683638 describes a study currently listed as recruiting. It is categorized as Phase 2, which is the standard way researchers label where a study sits along the investigational pathway from early safety work through later efficacy and post-marketing evaluation. The registered enrollment target is 15 participants, a figure that helps gauge the scale of data the investigators plan to collect. The listed sponsor is University of Washington, which has 987 total studies on file at ClinicalTrials.gov, and sponsors are the parties responsible for study design, oversight, and regulatory filings.
The record links to 1 condition, with Syphilis appearing as the primary indexed condition, and to 1 intervention — of which Doxycycline 200mg daily for 14 days is the first listed. Interventions can include drugs, devices, procedures, behavioral programs, or observational arms, and each is tracked as a separate registry field so that downstream queries can filter accurately. When a trial lists multiple interventions, it usually reflects a multi-arm design or a comparison protocol rather than a single treatment being tested in isolation. The brief summary published in the registry is the clearest source of protocol intent and should be read before drawing conclusions from any sidebar tags.
Geographic footprint matters for practical reasons: NCT06683638 reports 1 study location spanning 1 distinct geographic area — top geographies include Washington. A larger site network tends to correlate with broader recruitment capacity, but it does not imply anything about study quality, and site-level enrollment status can diverge from the overall registry status shown above. Every data point on this page comes from the public ClinicalTrials.gov dataset and is reproduced here for reference only; it is not a medical recommendation, an endorsement of the sponsor, or an invitation to enroll. Verify current status, eligibility criteria, and contact details directly at ClinicalTrials.gov, and discuss any participation decision with your own healthcare provider.
Frequently Asked Questions
What is clinical trial NCT06683638 about?
NCT06683638 is a clinical study titled "Daily Doxycycline for Early Syphillis". 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 ...
What is the current status of trial NCT06683638?
This trial is currently recruiting. It is a Phase 2 study. The enrollment target is 15 participants. The study started on 2025-03-03. Estimated completion is 2026-06-26.
What conditions does trial NCT06683638 study?
This clinical trial studies the following conditions: Syphilis. These conditions were identified from the trial registry and reflect the primary focus areas of the research.
What interventions are being tested in trial NCT06683638?
The interventions under investigation include: Doxycycline 200mg daily for 14 days (DRUG). Each intervention is being evaluated for safety and efficacy as part of this clinical study.
Who is sponsoring clinical trial NCT06683638?
This trial is sponsored by University of Washington, which has 987 total clinical trials registered on ClinicalTrials.gov. The sponsor is responsible for the study's design, funding, and regulatory compliance.
Where is trial NCT06683638 being conducted?
This trial has 1 study location across Washington. Contact the study sites directly through ClinicalTrials.gov for enrollment availability.
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