Sexually Transmitted InfectionPhase 4NCT06545656
Daily Doxycycline to Inform Sexually Transmitted Infection Prophylaxis Regimens
A Phase 4 study testing Doxycycline in people with Sexually Transmitted Infection, run by Emory University at 1 site in United States.
Trial summary
The goal of this project is to collect data regarding the concentrations of doxycycline in mucosal tissues after daily dosing for 7 days in people assigned male sex at birth (AMAB) and assigned female sex at birth (AFAB) to inform future studies of doxycycline to protect against bacterial sexually transmitted… Read more about this study
- Who is it for?
- Ages 18 to 59 yearsHealthy volunteers can take part
- Conditions the study is for
- Sexually Transmitted Infection
- What is being tested?
- Doxycycline
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 24 participants
- Where
- 1 siteUnited States
- Study dates
- 13 Sep 2024to 29 Apr 2025
- Phase
- Phase 4
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 59 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Assigned male sex or female sex at birth
- In good general health
- Not currently taking doxycycline or other tetracycline-derived antibiotics and no plans to initiate during the study
- For HIV positive people, on stable antiretroviral therapy with an undetectable viral load and cluster of differentiation 4 (CD4) count> 300ul/ml
- Willing to use condoms consistently for the duration of the study
- Able to provide informed consent
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- No plans for relocation in the next 4 months
- Not pregnant and does not plan on getting pregnant for the duration of the study
- Willing to undergo peripheral blood, urine, rectal or vaginal secretion collection, and a rectal or vaginal and cervical biopsy procedure
- Willing to use study products as directed
Who cannot join
- Current or chronic history of liver disease
- Continued need for, or use during the 90 days prior to enrollment, of the following medications:
- Systemic immunomodulatory agents
- Supraphysiologic doses of steroids (short course steroids less than 7 days duration, allowable at the discretion of the investigators)
- Chemotherapy or radiation for treatment of malignancy
- Experimental medications, vaccines, or biologicals
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- Intent to use doxycycline or other tetracycline-derived antibiotics during the course of the study, outside of the study procedures
- Any other clinical condition or prior therapy that, in the opinion of the investigator, would make the patient unsuitable for the study or unable to comply with the study requirements
- Known allergic reaction to study drugs
- Significant laboratory abnormalities at baseline visit for rectal biopsies, including but not limited to:
- Hemoglobin (Hgb) ≤ 10 g/dL
- Partial thromboplastin time (PTT) > 1.5x upper limit of normal (ULN) or international normalised ratio (INR) > 1.5x ULN
- Platelet count <100,000
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Daily Doxy: Study of Persons Receiving Daily Doxycycline to Inform Sexually Transmitted Infection Prophylaxis Regimens
The goal of this project is to collect data regarding the concentrations of doxycycline in mucosal tissues after daily dosing for 7 days in people assigned male sex at birth (AMAB) and assigned female sex at birth (AFAB) to inform future studies of doxycycline to protect against bacterial sexually transmitted infections (STIs).
Read the detailed description
Recent studies have demonstrated the potential utility of single-dose oral doxycycline postexposure prophylaxis (Doxy-PEP) against bacterial sexually transmitted infections (STIs). Additional dosing strategies are being explored that would also provide protection from bacterial STIs. However, the pharmacokinetics of daily doxycycline and specifically the effect of this dosing on effective drug levels in mucosal tissues is underexplored. A previous pilot study conducted by the Division of human immunodeficiency virus (HIV) Prevention (DHP) Laboratory Branch at the Centers for Disease Control and Prevention (CDC) examined the ability of a single 100mg oral dose of doxycycline to penetrate the vaginal and rectal mucosa. However, data regarding daily doxycycline doses and accumulation of doxycycline with multiple doses are lacking.
The purpose of this project is to collect data regarding the ability of daily oral doxycycline taken for 7 days to concentrate in mucosal tissues in people assigned male sex at birth (AMAB) and assigned female sex at birth (AFAB). Results from this study will be compared to results of the previous pilot studies conducted by the DHP Laboratory Branch at CDC.
Healthy people assigned male or female sex at birth will take the first dose of doxycycline during the enrollment visit (Hour -144/Day -6) then will take the next 5 doses at home, one per day for the next 5 days. After 6 consecutive days of dosing, study participants will have samples collected (Hour 0/Day 0) and then will take the final dose. Rectal and vaginal swab samples will be obtained 2 to 4 hours after the final dose of doxycycline. Rectal and vaginal biopsy tissue will be collected 24 hours after the last dose.
- Conditions
- Sexually Transmitted Infection
- Being tested
- Doxycycline
- Medical subject headings
- Sexually Transmitted Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
DoxycyclineDrug
Also called Doxy-100, Oracea, Monodox
Doxycycline (DOX) will be given orally at 100mg doses. Participants will take the study medication for 7 consecutive days.
| Study group | Role | What they receive |
|---|---|---|
| Doxycycline | Experimental | Study participants taking 7 consecutive, daily doses of 100mg of Doxycycline. Receives: Drug: Doxycycline |
What is being measured
The primary outcome is the main question the study is designed to answer.
Doxycycline Concentration in Rectal Tissue
Rectal tissue doxycycline concentrations collected 24 hours after 7 daily (T7) doses of 100 mg of doxycycline were determined in assigned male sex at birth (AMAB) participants.
Measured: 24 hours after last dose (Hour 24/Day 1)
Doxycycline Concentration in Vaginal Tissue
Vaginal tissue doxycycline concentrations collected 24 hours after 7 daily (T7) doses of 100 mg of doxycycline were determined in Assigned female sex at birth (AFAB) participants.
Measured: 24 hours after last dose (Hour 24/Day 1)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Aug 2024
- Study start13 Sep 2024
- Primary completion29 Apr 2025
- Study completion29 Apr 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Sexually Transmitted InfectionStudies of the same condition, open and under way.
- More trials run by Emory UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- This study aims to enroll a minimum of 10 AFAB and 10 AMAB participants.
- Masking
- None (open label)
- Enrolment
- 24 participants (actual)
Sponsor and investigators
- Lead sponsor
- Emory University
- Sponsor type
- University, hospital or other
- Collaborators
- Centers for Disease Control and Prevention
- Responsible party
- Principal investigator, Colleen Kelley, Emory University
- Investigators
- Colleen Kelley, MD, MPH, Principal investigator, Emory University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06545656
- Sponsor's protocol ID
- STUDY00007429
- Other IDs
- CDC-STUDY00007429
- Status last verified
- Jun 2025
- First submitted
- 6 Aug 2024
- Last updated
- 1 May 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data underlie the results published for this study (including text, tables, figures, and appendices) will be made available for sharing with other researchers.
Publications
Daly MB, Spandau M, Edwards TE, Dinh C, Fountain J, Dienhart JA, Conway-Washington C, Kelley C, Heneine W, Haaland R. Chelating anticoagulants reduce plasma doxycycline measurements: implications for doxy PEP monitoring. Expert Rev Clin Pharmacol. 2026 Jan-Feb;19(2):199-205. doi: 10.1080/17512433.2026.2632931. Epub 2026 Feb 19.
PubMed 41701614
Study at a glance
From the registry record, last updated by the sponsor on 1 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Daily Doxy: Study of Persons Receiving Daily Doxycycline to Inform Sexually Transmitted Infection Prophylaxis Regimens
- ClinicalTrials.gov ID
- NCT06545656
- Acronym / sponsor ID
- STUDY00007429
- Conditions
- Sexually Transmitted Infection
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 24 participants (actual)
- Lead sponsor
- Emory UniversityUniversity, hospital or other
- Collaborators
- Centers for Disease Control and Prevention
- Study start
- 13 Sep 2024 (actual)
- Primary completion
- 29 Apr 2025 (actual)
- Study completion
- 29 Apr 2025 (actual)
- First posted
- 9 Aug 2024 (actual)
- Results
- Posted 1 May 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this project is to collect data regarding the concentrations of doxycycline in mucosal tissues after daily dosing for 7 days in people assigned male sex at birth (AMAB) and assigned female sex at birth (AFAB) to inform future studies of doxycycline to protect against bacterial sexually transmitted infections (STIs).
Detailed description
Recent studies have demonstrated the potential utility of single-dose oral doxycycline postexposure prophylaxis (Doxy-PEP) against bacterial sexually transmitted infections (STIs). Additional dosing strategies are being explored that would also provide protection from bacterial STIs. However, the pharmacokinetics of daily doxycycline and specifically the effect of this dosing on effective drug levels in mucosal tissues is underexplored. A previous pilot study conducted by the Division of human immunodeficiency virus (HIV) Prevention (DHP) Laboratory Branch at the Centers for Disease Control and Prevention (CDC) examined the ability of a single 100mg oral dose of doxycycline to penetrate the vaginal and rectal mucosa. However, data regarding daily doxycycline doses and accumulation of doxycycline with multiple doses are lacking.
The purpose of this project is to collect data regarding the ability of daily oral doxycycline taken for 7 days to concentrate in mucosal tissues in people assigned male sex at birth (AMAB) and assigned female sex at birth (AFAB). Results from this study will be compared to results of the previous pilot studies conducted by the DHP Laboratory Branch at CDC.
Healthy people assigned male or female sex at birth will take the first dose of doxycycline during the enrollment visit (Hour -144/Day -6) then will take the next 5 doses at home, one per day for the next 5 days. After 6 consecutive days of dosing, study participants will have samples collected (Hour 0/Day 0) and then will take the final dose. Rectal and vaginal swab samples will be obtained 2 to 4 hours after the final dose of doxycycline. Rectal and vaginal biopsy tissue will be collected 24 hours after the last dose.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- This study aims to enroll a minimum of 10 AFAB and 10 AMAB participants.
| Arm | Type | Receives |
|---|---|---|
| Doxycycline | Experimental | Drug: DoxycyclineStudy participants taking 7 consecutive, daily doses of 100mg of Doxycycline. |
Who may qualify
- Ages
- 18 to 59 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (10 listed)
- Assigned male sex or female sex at birth
- In good general health
- Not currently taking doxycycline or other tetracycline-derived antibiotics and no plans to initiate during the study
- For HIV positive people, on stable antiretroviral therapy with an undetectable viral load and cluster of differentiation 4 (CD4) count> 300ul/ml
- Willing to use condoms consistently for the duration of the study
Key exclusion criteria (13 listed)
- Current or chronic history of liver disease
- Continued need for, or use during the 90 days prior to enrollment, of the following medications:
- Intent to use doxycycline or other tetracycline-derived antibiotics during the course of the study, outside of the study procedures
- Any other clinical condition or prior therapy that, in the opinion of the investigator, would make the patient unsuitable for the study or unable to comply with the study requirements
- Known allergic reaction to study drugs
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| DoxycyclineAlso: Doxy-100, Oracea, MonodoxDoxycycline (DOX) will be given orally at 100mg doses. Participants will take the study medication for 7 consecutive days. | Drug | Doxycycline |
Primary outcome
Doxycycline Concentration in Rectal Tissue
Time frame: 24 hours after last dose (Hour 24/Day 1)
Rectal tissue doxycycline concentrations collected 24 hours after 7 daily (T7) doses of 100 mg of doxycycline were determined in assigned male sex at birth (AMAB) participants.
Doxycycline Concentration in Vaginal Tissue
Time frame: 24 hours after last dose (Hour 24/Day 1)
Vaginal tissue doxycycline concentrations collected 24 hours after 7 daily (T7) doses of 100 mg of doxycycline were determined in Assigned female sex at birth (AFAB) participants.
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 May 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 41701614Daly MB, Spandau M, Edwards TE, Dinh C, Fountain J, Dienhart JA, Conway-Washington C, Kelley C, Heneine W, Haaland R. Chelating anticoagulants reduce plasma doxycycline measurements: implications for doxy PEP monitoring. Expert Rev Clin Pharmacol. 2026 Jan-Feb;19(2):199-205. doi: 10.1080/17512433.2026.2632931. Epub 2026 Feb 19.
- Individual participant dataSharing planned: Yes. De-identified individual participant data underlie the results published for this study (including text, tables, figures, and appendices) will be made available for sharing with other researchers.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Colleen Kelley, MD, MPH principal investigator
Emory University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Doxycycline in people with Sexually Transmitted Infection, run by Emory University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 10 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 1 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 1 May 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Doxycycline Concentration in Rectal Tissue (time frame: 24 hours after last dose (Hour 24/Day 1)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06545656, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 May 2026.