NCT06414408 · University of California, San Francisco
Randomized Directly Observed Therapy Study to Interpret Clinical Trials of Doxy-PEP
(DOT-Doxy-PEP)
What this study is about
Rates of bacterial sexually transmitted infections (STIs) are rising globally, demanding innovative interventions beyond the scope of current efforts to prevent STIs.
View original scientific description
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.
Interventions
DRUG
Doxycycline Pill
200mg Dose
Primary outcome measures
Hair Doxycycline Concentration
Time frame: 4 weeks
Doxycycline concentrations will be measured using liquid chromatography tandem mass spectrometry within hair samples for each of the four dosing patterns within an intensive washout pharmacokinetic phase following initial dosing.
Plasma Doxycycline Concentration
Time frame: 4 weeks
Doxycycline concentrations will be measured using liquid chromatography tandem mass spectrometry within plasma samples for each of the four dosing patterns within an intensive washout pharmacokinetic phase following initial dosing.
Urine Doxycycline Concentration
Time frame: 4 weeks
Doxycycline concentrations will be measured using liquid chromatography tandem mass spectrometry within urine samples for each of the four dosing patterns within an intensive washout pharmacokinetic phase following initial dosing.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- not currently at risk of a sexually transmitted infection and willing to use other methods, such as condoms, for STI prevention;
- if diagnosed with an STI in the past two years and/or a partner was diagnosed with an STI in the past year, is willing to use condoms for STI prevention;
- willing to provide hair, blood, and urine samples;
- not currently enrolled in other STI prevention studies;
- able to speak English
- 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
- able to provide a hair sample of \~50-100 strands of hair that are non-gray, not bleached, and at least 1cm in length
- willing to NOT shave hair or have a very short haircut or apply bleach for the duration of the study
- has suitable venous access for consecutive blood draws
Exclusion criteria
- 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.
- unable to provide a hair sample of \~50-100 strands of hair that are non-gray, not bleached, and at least 1cm in length
- does not have suitable venous access for consecutive blood draws
Where
- San Francisco, California
Collaborators
National Institute of Allergy and Infectious Diseases (NIAID)
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Apr 13, 2026 · Source of record for eligibility and locations