The goal of this project is to collect data regarding the ability of various oral doses of doxycycline to penetrate mucosal tissues in men and women to inform the combination of doxycycline with antiretrovirals (ARVs) for the development of single-dose event-driven multipurpose prevention strategies to protect against HIV and sexually transmitted infections (STIs).

This study is of importance in the field of research because it allows the exploration of new dosing strategies that would permit a single event-driven oral dose of medications that could provide protection from HIV as well as other STIs.

The study population that this study seeks to enroll are healthy people assigned male or female sex at birth and not using gender-affirming hormone therapy and are willing to undergo study procedures.

Recruitment: Both face-to-face and online engagements will be conducted to recruit study participants. Face-to-face locations include bars and nightclubs, community organizations serving study populations, sports events, and community venues, and online engagements include dating sites, social networks, and craigslist, amongst other social medial platforms.

The incidence of bacterial STIs is increasing and studies have recently shown that Doxy-PEP can reduce the incidence of bacterial STIs among men who have sex with men (MSM) and Doxy-PEP is being explored for STI prevention among women.

A better understanding of mucosal drug penetration of doxycycline will inform the design of future studies to prevent STIs in various populations. The purpose of this study is to understand how well doxycycline taken by mouth gets to the tissues of the rectum and vagina. Researchers think doxycycline could be used to treat sexually transmitted infections (STIs) caused by bacteria. To understand better, they want to see how well doxycycline reaches the tissues affected by STIs.

The study procedures include the collection of past and present medical history, and biological specimen sampling such as blood, rectal and vaginal fluids, tissue biopsies, and urine. Study participants will also be administered an investigational agent (doxycycline not yet approved for this indication).

The duration of this clinical trial for study participants will be approximately 8 weeks.

Inclusion Criteria:

• Aged 18-59 years
• 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 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

Exclusion Criteria:

• Current or chronic history of liver disease

• Continued need for, or use during the 90 days before enrollment, of the following medications:

  1. Systemic immunomodulatory agents
  2. Supraphysiologic doses of steroids (short course steroids less than 7 days duration, allowable at the discretion of the investigators)
  3. Chemotherapy or radiation for treatment of malignancy
  4. Experimental medications, vaccines, or biologicals

• Intent to use doxycycline or other tetracycline-derived antibiotics during 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:

  1. Hgb ≤ 10 g/dL
  2. PTT > 1.5x ULN or INR > 1.5x ULN
  3. Platelet count <100,000

Individual participant data that underlie the results published for this study (including text, tables, figures, and appendices), will be made available for sharing, after de-identification.

The research team will share de-identified participant data after the primary manuscript publication.

Interested investigators can request deidentified data by email for secondary data analyses and/or meta-analyses.

Information on adverse events was collected from the time consent to participate in the study was given through 3 months after the fifth dose of the study intervention, for a total duration of approximately 3.5 months.