Transgender PersonsNCT05116293
Effect of Testosterone Treatment on Drug Metabolism and Transport
An observational study of Transgender Persons, run by University of Washington at 1 site in United States.
Trial summary
This project will evaluate the effect of gender-affirming testosterone treatment on how other medications are processed by the body. Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Transgender Persons
- What is being tested?
- Midazolam oral solution, Digoxin Oral Tablet and Acetaminophen Oral Tablet
- Type of treatment
- Pill or oral medicine
- How many people
- 14 participants
- Where
- 1 siteUnited States
- Study dates
- 1 May 2021to 31 Dec 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: Transgender adults planning to take testosterone treatment.
Who may be able to join
- Self-identified trans* adult at least 18 years of age.
- Not taking testosterone treatment currently.
- Planning to start testosterone treatment through care provider for gender-affirming medical care.
Who cannot join
- Unwilling/unable to return for project follow-up visits.
- Unwilling/unable to provide written informed consent.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effect of Gender-Affirming Testosterone Therapy on Drug Metabolism, Transport, and Gut Microbiota
This project will evaluate the effect of gender-affirming testosterone treatment on how other medications are processed by the body.
Read the detailed description
Gender-affirming hormone therapy may include testosterone, a hormone that the body creates and uses naturally. Testosterone is prepared as a medication that patients may take to increase hormone levels. Changes in testosterone concentrations in the body may affect how the body processes other medicines. The purpose of this study is to find out how testosterone therapy affects a single tracer dose of approved medicines in the blood (midazolam, digoxin, and acetaminophen) and to confirm testosterone treatment does not affect natural bacterial in the gut.
- Conditions
- Transgender Persons
- Being tested
- Midazolam oral solution, Digoxin Oral Tablet, Acetaminophen Oral Tablet
- Keywords
- Testosterone Treatment
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Midazolam oral solutionDrug
Oral syrup
Digoxin Oral TabletDrug
Oral tablet
Acetaminophen Oral TabletDrug
Oral tablet
What is being measured
The primary outcome is the main question the study is designed to answer.
midazolam AUC ratio (treatment/control)
ratio of the area under of the plasma concentration time curve (AUC) of midazolam in the presence to absence of gender-affirming testosterone treatment.
Measured: 0-48 hours
Secondary outcomes (1)
midazolam Cmax ratio (treatment/control)
ratio of the maximum plasma concentration (Cmax) of midazolam in the presence to absence of gender-affirming testosterone treatment
Measured: 0-48 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 Nov 2021
- Study start1 May 2021
- Primary completion15 Feb 2024
- Study completion31 Dec 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Transgender PersonsStudies of the same condition, open and under way.
- More trials run by University of WashingtonThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 14 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Washington
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Lauren Cirrincione, University of Washington
- Investigators
- Lauren Cirrincione, MPH,Pharm D, Principal investigator, University of Washington
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05116293
- Sponsor's protocol ID
- STUDY00011644
- Status last verified
- Apr 2026
- First submitted
- 15 Oct 2021
- Last updated
- 4 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Hunter M, Coig R, Risler L, Patton KK, Narla RR, Greene DN, Burke AK, Micks E, Hebert MF, Cirrincione LR. Effect of Testosterone Therapy on Cytochrome P450 3A and P-Glycoprotein Activities Using Midazolam and Digoxin as Probe Substrates Among Transgender Adults. Pharmacotherapy. 2026 Feb;46(2):e70093. doi: 10.1002/phar.70093. Epub 2025 Dec 26.
PubMed 41452771
Study at a glance
From the registry record, last updated by the sponsor on 4 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Gender-Affirming Testosterone Therapy on Drug Metabolism, Transport, and Gut Microbiota
- ClinicalTrials.gov ID
- NCT05116293
- Acronym / sponsor ID
- STUDY00011644
- Conditions
- Transgender Persons
- Keywords
- Testosterone Treatment
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 14 participants (actual)
- Lead sponsor
- University of WashingtonUniversity, hospital or other
- Study start
- 1 May 2021 (actual)
- Primary completion
- 15 Feb 2024 (actual)
- Study completion
- 31 Dec 2025 (actual)
- First posted
- 11 Nov 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This project will evaluate the effect of gender-affirming testosterone treatment on how other medications are processed by the body.
Detailed description
Gender-affirming hormone therapy may include testosterone, a hormone that the body creates and uses naturally. Testosterone is prepared as a medication that patients may take to increase hormone levels. Changes in testosterone concentrations in the body may affect how the body processes other medicines. The purpose of this study is to find out how testosterone therapy affects a single tracer dose of approved medicines in the blood (midazolam, digoxin, and acetaminophen) and to confirm testosterone treatment does not affect natural bacterial in the gut.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Transgender adults planning to take testosterone treatment.
Key inclusion criteria (3 listed)
- Self-identified trans* adult at least 18 years of age.
- Not taking testosterone treatment currently.
- Planning to start testosterone treatment through care provider for gender-affirming medical care.
Key exclusion criteria (2 listed)
- Unwilling/unable to return for project follow-up visits.
- Unwilling/unable to provide written informed consent.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Midazolam oral solutionOral syrup | Drug | – |
| Digoxin Oral TabletOral tablet | Drug | – |
| Acetaminophen Oral TabletOral tablet | Drug | – |
Primary outcome
midazolam AUC ratio (treatment/control)
Time frame: 0-48 hours
ratio of the area under of the plasma concentration time curve (AUC) of midazolam in the presence to absence of gender-affirming testosterone treatment.
1 secondary outcome
midazolam Cmax ratio (treatment/control)
Time frame: 0-48 hours
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 4 May 2026.
- Derived from this study: PubMed 41452771Hunter M, Coig R, Risler L, Patton KK, Narla RR, Greene DN, Burke AK, Micks E, Hebert MF, Cirrincione LR. Effect of Testosterone Therapy on Cytochrome P450 3A and P-Glycoprotein Activities Using Midazolam and Digoxin as Probe Substrates Among Transgender Adults. Pharmacotherapy. 2026 Feb;46(2):e70093. doi: 10.1002/phar.70093. Epub 2025 Dec 26.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Lauren Cirrincione, MPH,Pharm D principal investigator
University of Washington
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Transgender Persons, run by University of Washington at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 4 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
midazolam AUC ratio (treatment/control) (time frame: 0-48 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05116293, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 4 May 2026.