Daily Doxycycline to Inform Sexually Transmitted Infection Prophylaxis Regimens

NCT06545656 | Completed Phase 4 Results FDA Drug

• 2 other identifiers: STUDY00007429CDC-STUDY00007429
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief 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 infections (STIs).

Conditions

Sexually Transmitted Infection

Outcome Measures

Primary Outcomes (2)

• 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.

  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.

  24 hours after last dose (Hour 24/Day 1)

Study Arms (1)

Doxycycline

EXPERIMENTAL

Study participants taking 7 consecutive, daily doses of 100mg of Doxycycline.

Drug: Doxycycline

Interventions

Doxycycline DRUG

Doxycycline (DOX) will be given orally at 100mg doses. Participants will take the study medication for 7 consecutive days.

Also known as: Doxy-100, Oracea, Monodox

Doxycycline

Eligibility Criteria

• Age: 18 Years - 59 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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
• 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

You may not qualify if:

• 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
• 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

Sponsors & Collaborators

• Emory University: lead
• Centers for Disease Control and Prevention: collaborator

Study Sites (1)

Hope Clinic

Atlanta, Georgia, 30322, United States

Location

Related Publications (1)

• 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.

  PMID: 41701614 DERIVED

MeSH Terms

Conditions

Sexually Transmitted Diseases

Interventions

Doxycycline

Condition Hierarchy (Ancestors)

Communicable Diseases; Infections; Genital Diseases; Urogenital Diseases; Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Tetracyclines; Naphthacenes; Polycyclic Aromatic Hydrocarbons; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals; Polycyclic Compounds

Results Point of Contact

• Title: Dr. Colleen F. Kelley
• Organization: Emory University

colleen.kelley@emory.edu

404-712-1823

Study Officials

• Colleen Kelley, MD, MPH

  Emory University

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: Yes

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Model Details: This study aims to enroll a minimum of 10 AFAB and 10 AMAB participants.

Study Record Dates

• First Submitted: August 6, 2024
• First Posted: August 9, 2024
• Study Start: September 13, 2024
• Primary Completion: April 29, 2025
• Study Completion: April 29, 2025
• Last Updated: May 1, 2026
• Results First Posted: May 1, 2026

Record last verified: 2025-06

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: Individual participant data will be made available for sharing after publication of the primary manuscript from this study.
• Access Criteria: Interested investigators can request de-identified data by email for secondary data analyses and/or meta-analyses.

Locations

US (1)