for people ages 18 years and up (full criteria)
Healthy Volunteers
healthy people welcome
at San Francisco, California
study started
completion around
Principal Investigator
by Matthew Spinelli, MD, MAS
Headshot of Matthew Spinelli
Matthew Spinelli



Rates of bacterial sexually transmitted infections (STIs) are rising globally, demanding innovative interventions beyond the scope of current efforts to prevent STIs. The United States Doxycycline Post-exposure Prophylaxis (DoxyPEP) Study has demonstrated the efficacy of doxycycline post-exposure prophylaxis (PEP) among men who have sex with men and transgender women; but puzzlingly, doxycycline PEP was found ineffective in cisgender women in the Kenyan doxycycline Post-Exposure Prophylaxis (dPEP) study, with preliminary data suggesting the low medication adherence may explain the null result. By study end, the investigators will have developed adherence measurement methods for doxycycline in hair, blood, and urine, and will use these techniques to help interpret the Kenyan dPEP study, and to examine the relative performance of these methods within the United States DoxyPEP trial, establishing adherence metrics for current and future rollout studies of doxycycline post-exposure prophylaxis


Sexually Transmitted Diseases, Bacterial, Sexually Transmitted Diseases, Bacterial Sexually Transmitted Diseases, Doxycycline, Doxycycline Pill, Every Other Week Dosing


You can join if…

Open to people ages 18 years and up

  • not currently at risk of a sexually transmitted infection (no STI in the last 2 years and no partner with an STI in the last year);
  • willing to provide hair, blood, and urine samples;
  • not currently enrolled in other STI prevention studies;
  • able to speak English or Spanish; and
  • transgender women participants should be currently using estrogen gender affirming hormone therapy with blood estrogen levels demonstrating consistent use
  • transgender men participants should be currently using testosterone gender affirming hormone therapy with blood testosterone levels demonstrating consistent use

You CAN'T join if...

  • any health condition that may interfere with participation or the ability to provide informed consent, including any debilitating or life-threatening conditions;
  • pregnancy or plans to become pregnant;
  • liver cirrhosis or fulminant liver disease;
  • known hypersensitivity reaction to doxycycline.
  • detectable doxycycline in hair at enrollment.


  • UCSF/San Francisco General Hospital
    San Francisco California 94110 United States

Lead Scientist at UCSF

  • Matthew Spinelli, MD, MAS
    I am HIV/ID physician with training in implementation science methods who uses these approaches to support pre-exposure prophylaxis (PrEP) implementation, PrEP/HIV ART adherence, and PrEP persistence/HIV retention in care. A key tool we are using in this work is a point-of-care urine tenofovir test that can provide real-time adherence information to clinicians to drive adherence interventions.


not yet accepting patients
Start Date
Completion Date
University of California, San Francisco
Phase 1 Sexually Transmitted Infections Research Study
Study Type
Expecting 48 study participants
Last Updated