A Phase 1 interventional study of Single-Dose PK Phase - DR Group and Single-Dose PK Phase - IR Group in Sexually Transmitted Infection, sponsored by HIV Prevention Trials Network. Enrolling by invitation at 1 site in United States. Open to participants aged 18 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-17.
Sponsored by HIV Prevention Trials Network · Phase 1, Interventional, and Basic science
The purpose of this study is to evaluate the effect of body changes on doxycycline concentrations for different dosing schedules. This study will involve a single dose phase and a multiple dose phase. Healthy individuals who do not have a sexually transmitted infection (STI), including acute (e.g., gonorrhea or chlamydia) or chronic (e.g., HIV or HSV-2) infections will be enrolled in this study. Study participants will be randomized to a dosing schedule in each phase and come to the research clinic throughout their time on study for sample collection. Study participants that choose to enroll in this study will be enrolled for about 37 days.
Doxycycline is a Food and Drug Administration (FDA) approved broad-spectrum, second-generation tetracycline antibiotic that is generally well-tolerated and has been widely used as primary prophylaxis for bacterial and parasitic infections. While the pharmacokinetics (PK) of doxycycline in blood are well-described, knowledge gaps exist with intermittent dosing and establishing adherence thresholds for prophylactic use. Further, the multi-compartment distribution of the doxycycline has not been extensively characterized. The purpose of this study will be to characterize pharmacologic parameters for daily and non-daily doxycycline use and establish adherence cutoffs for daily and non-daily use.
523 studies on the registry are indexed under Sexually Transmitted Diseases; 77 are open to participants now.
This study's planned enrollment of 16 is below the median of 449 across 425 interventional studies indexed under Sexually Transmitted Diseases.
Browse Sexually Transmitted Diseases studies →HIV Prevention Trials Network is the lead sponsor of 24 studies on the registry; 4 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
For females of reproductive potential: Using at least two effective methods of for at least 30 days (inclusive) prior to enrollment and intending to use two effective methods of contraception for the duration of study participation. It is strongly recommended that at least one barrier method (e.g. condoms) in addition to a hormonal contraception method be used. Examples of acceptable and effective methods include:
Exclusion Criteria:
Has any of the following laboratory abnormalities:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Able to have children. For women this usually means from the first period until menopause, unless permanently unable to through surgery; for men, unless permanently sterile. Read who the line is about — participants, women, men, or their partners.
Criteria about it usually ask for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Reproductive potential
Able to have children. For women this usually means from the first period until menopause, unless permanently unable to through surgery; for men, unless permanently sterile. Read who the line is about — participants, women, men, or their partners.
Criteria about it usually ask for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants in this arm will take one 200 mg delayed release (DR) doxycycline hyclate tablet
Drug: Single-Dose PK Phase - DR Group
Participants randomized to this arm will receive one 200mg doxycycline hyclate delayed release (DR) tablet daily (every 24 hours) for 10 days.
Drug: Multi-Dose PK Phase - Daily Group
Participants in this arm will take two 100mg immediate release (IR) doxycycline hyclate tablets
Drug: Single-Dose PK Phase - IR Group
Participants randomized to this arm will receive one 200mg doxycycline hyclate delayed release (DR) tablet intermittently (every 72 hours) for 10 days.
Drug: Multi-Dose PK Phase - Intermittent Group
One 200 mg doxycycline hyclate delayed release (DR) tablet
Two 100 mg doxycycline hyclate immediate-release (IR) tablets
One 200 mg doxycycline hyclate delayed release (DR) tablet every 24 hours
One 200 mg doxycycline hyclate delayed release (DR) tablet every 72 hours
Maximum observed plasma concentration (Cmax) for 200mg doxycycline hyclate after a single dose.
Median (IQR) plasma doxycycline hyclate Cmax (ng/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Minimum observed plasma concentration (Cmin) for 200mg doxycycline hyclate after a single dose.
Median (IQR) plasma doxycycline hyclate Cmin (ng/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Time to reach maximum plasma concentration (Tmax) of 200mg doxycycline hyclate after a single dose.
Median (IQR) plasma doxycycline hyclate Tmax (hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Plasma half-life (T1/2) of 200mg doxycycline hyclate after a single dose.
Median (IQR) plasma doxycycline hyclate half-life (T1/2, hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Area Under the Concentration-Time Curve in plasma From One to 336 Hours After Dosing (AUC0-24) of 200mg doxycycline hyclate.
Median (IQR) plasma doxycycline hyclate area under the concentration time curve (AUC)0-inf (ng\*hr/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Plasma concentrations at 24 hours (C24) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) plasma concentration at 24 hours post last dose (ng/mL units)
Time frame: 24 hours post last dose of the multiple dose phase.
Plasma concentrations at 48 hours (C48) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) plasma concentration at 48 hours post last dose (ng/mL units)
Time frame: 48 hours post last dose of the multiple dose phase.
Plasma concentrations at 72 hours (C72) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) plasma concentration at 72 hours post last dose (ng/mL units)
Time frame: 72 hours post last doseof the multiple dose phase.
Number of gastrointestinal (GI)-related adverse events reported after doxycycline hyclate dosing during the multiple dose phase.
Number of GI-related adverse events during 10 days of daily or intermittent doxycycline dosing
Time frame: Study visit days 14-23
Number of gastrointestinal (GI)-related adverse events reported after doxycycline hyclate dosing after the multiple dose phase.
Number of GI-related adverse events for 14 days following final daily or intermittent dose (through the Final/Day 37 visit)
Time frame: Up to 14 days post last dose.
Maximum observed dried blood spot (DBS) concentration (Cmax) for 200mg doxycycline hyclate after a single dose.
Median (IQR) DBS doxycycline hyclate Cmax (ng/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Minimum observed dried blood spot (DBS) concentration (Cmin) for 200mg doxycycline hyclate after a single dose.
Median (IQR) DBS doxycycline hyclate Cmin (ng/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Time to reach maximum dried blood spot (DBS) concentration (Tmax) of 200mg doxycycline hyclate after a single dose.
Median (IQR) DBS doxycycline hyclate Tmax (hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Dried blood spot (DBS) half-life (T1/2) of 200mg doxycycline hyclate after a single dose.
Median (IQR) DBS doxycycline hyclate half-life (T1/2, hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Area Under the Concentration-Time Curve in dried blood spots (DBS) From One to 336 Hours After Dosing (AUC0-24) of 200mg doxycycline hyclate.
Median (IQR) DBS doxycycline hyclate area under the concentration time curve (AUC)0-inf (ng\*hr/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Maximum observed anorectal fluid concentration (Cmax) for 200mg doxycycline hyclate after a single dose.
Median (IQR) anorectal doxycycline hyclate Cmax (ng/swab units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Minimum observed anorectal fluid concentration (Cmin) for 200mg doxycycline hyclate after a single dose.
Median (IQR) anorectal doxycycline hyclate Cmin (ng/swab units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Time to reach maximum anorectal fluid concentration (Tmax) of 200mg doxycycline hyclate after a single dose.
Median (IQR) anorectal doxycycline hyclate Tmax (hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Anorectal fluid half-life (T1/2) of 200mg doxycycline hyclate after a single dose.
Median (IQR) anorectal doxycycline hyclate half-life (T1/2, hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Area Under the Concentration-Time Curve in anorectal fluid From One to 336 Hours After Dosing (AUC0-24) of 200mg doxycycline hyclate.
Median (IQR) anorectal doxycycline hyclate area under the concentration time curve (AUC)0-inf (ng\*hr/swab units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Maximum observed vaginal fluid concentration (Cmax) for 200mg doxycycline hyclate after a single dose.
Median (IQR) vaginal doxycycline hyclate Cmax (ng/swab units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Minimum observed vaginal fluid concentration (Cmin) for 200mg doxycycline hyclate after a single dose.
Median (IQR) vaginal doxycycline hyclate Cmin (ng/swab units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Time to reach maximum vaginal fluid concentration (Tmax) of 200mg doxycycline hyclate after a single dose.
Median (IQR) vaginal doxycycline hyclate Tmax (hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Vaginal fluid half-life (T1/2) of 200mg doxycycline hyclate after a single dose.
Median (IQR) vaginal doxycycline hyclate half-life (T1/2, hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Area Under the Concentration-Time Curve in vaginal fluid From One to 336 Hours After Dosing (AUC0-24) of 200mg doxycycline hyclate.
Median (IQR) vaginal doxycycline hyclate area under the concentration time curve (AUC)0-inf (ng\*hr/swab units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Maximum observed pooled urine concentration (Cmax) for 200mg doxycycline hyclate after a single dose.
Mean (95% CI) urine doxycycline hyclate Cmax (ng/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Minimum observed pooled urine concentration (Cmin) for 200mg doxycycline hyclate after a single dose.
Mean (95% CI) urine doxycycline hyclate Cmin (ng/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Time to reach maximum pooled urine concentration (Tmax) of 200mg doxycycline hyclate after a single dose.
Mean (95% CI) urine doxycycline hyclate Tmax (hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Pooled urine half-life (T1/2) of 200mg doxycycline hyclate after a single dose.
Mean (95% CI) urine doxycycline hyclate half-life (T1/2, hours units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Area Under the Concentration-Time Curve in urine From One to 336 Hours After Dosing (AUC0-24) of 200mg doxycycline hyclate.
Mean (95% CI) urine doxycycline hyclate area under the concentration time curve (AUC)0-inf (ng\*hr/mL units)
Time frame: 1, 2, 3, 4, 6, 8, 24, 72, 96, 168, 240, and 336 hours post dose.
Dried blood spot (DBS) concentrations at 24 hours (C24) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) DBS concentration at 24 hours post last dose (ng/mL units)
Time frame: 24 hours post last dose of the multiple dose phase.
Dried blood spot (DBS) concentrations at 48 hours (C48) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) DBS concentration at 48 hours post last dose (ng/mL units)
Time frame: 48 hours post last dose of the multiple dose phase.
Dried blood spot (DBS) concentrations at 72 hours (C72) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) DBS concentration at 72 hours post last dose (ng/mL units)
Time frame: 72 hours post last dose of the multiple dose phase.
Urine concentrations at 24 hours (C24) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) urine concentration at 24 hours post last dose (ng/mL units)
Time frame: 24 hours post last dose of the multiple dose phase.
Urine concentrations at 48 hours (C48) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) urine concentration at 48 hours post last dose (ng/mL units)
Time frame: 48 hours post last dose of the multiple dose phase.
Urine concentrations at 72 hours (C72) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) urine concentration at 72 hours post last dose (ng/mL units)
Time frame: 72 hours post last dose of the multiple dose phase.
Anorectal fluid concentrations at 24 hours (C24) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) anorectal concentration at 24 hours post last dose (ng/swab units)
Time frame: 24 hours post last dose of the multiple dose phase.
Anorectal fluid concentrations at 48 hours (C48) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) anorectal concentration at 48 hours post last dose (ng/swab units)
Time frame: 48 hours post last dose of the multiple dose phase.
Anorectal fluid concentrations at 72 hours (C72) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) anorectal concentration at 72 hours post last dose (ng/swab units)
Time frame: 72 hours post last dose of the multiple dose phase.
Vaginal fluid concentrations at 24 hours (C24) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) vaginal concentration at 24 hours post last dose (ng/swab units)
Time frame: 24 hours post last dose of the multiple dose phase.
Vaginal fluid concentrations at 48 hours (C48) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) vaginal concentration at 48 hours post last dose (ng/swab units)
Time frame: 48 hours post last dose of the multiple dose phase.
Vaginal fluid concentrations at 72 hours (C72) post last dose of doxycycline following 10 days of daily or intermittent dosing.
Median (IQR) vaginal concentration at 72 hours post last dose (ng/swab units)
Time frame: 72 hours post last dose of the multiple dose phase.
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes — For studies within two years of primary objective(s) publication, de-identified individual participant data that underlie results in a publication, will be provided upon request. For studies more than two years from the primary objective(s) publication, de-identified datasets will be available upon request (Public Use Datasets).
Supporting information: Study protocol, Statistical analysis plan
Time frame: Investigators may request de-identified datasets in order to duplicate published results, as required by specific journals. Otherwise, de-identified datasets will be made available upon request, two years following publication of the primary results manuscript.
Access criteria: Researchers may submit a request for access to data that has informed published results, by sending an email to HPTN-Data-Access@scharp.org. To access available de-identified datasets, investigators must complete the request form on the Atlas website. Researchers of approved requests will need to sign an HPTN Data Use Agreement before receiving the data and agree to use the provided acknowledgement statement.
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