Skip to main content
OpenTrials
Completed

NCT Number: NCT05469204

Effect of Estrogen Treatment on Drug Metabolism and Transport

This project will evaluate the effect of estrogen treatment on how other medications are processed by the body.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Transgender Persons

Age range

18 year–55 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

University of Washington

Seattle, Washington, 98195, United States

About this study

Estradiol is prepared as a medication that patients may take to increase hormone levels. Changes in estradiol concentrations in the body may affect how the body processes other medicines. The purpose of this study is to find out how estradiol therapy affects a single tracer dose of approved medicines in the blood (midazolam, digoxin, and acetaminophen) and to confirm estradiol treatment does not affect natural bacterial in the gut.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Self-identified trans* adult 18-55 years of age.
  • Not taking estradiol treatment currently.
  • Planning to start injectable estradiol or estradiol tablets for gender-affirming medical care.

Exclusion criteria

  • Unwilling/unable to return for project follow-up visits.
  • Unwilling/unable to provide written informed consent.

Treatment and study plan

Midazolam oral solution

Drug

2 mg single-dose before and during estradiol treatment.

Digoxin Oral Tablet

Drug

0.25 mg single-dose before and during estradiol treatment.

Acetaminophen Oral Tablet

Drug

500 mg single-dose before and during estradiol treatment.

Midazolam Injectable Solution

Drug

1 mg intravenous single-dose before and during estradiol treatment.

Primary outcomes

  1. midazolam AUC ratio (treatment/control)

    Time frame: 0-6 hours

    ratio of the area under of the plasma concentration time curve (AUC) of midazolam in the presence to absence of gender-affirming estradiol treatment.

  2. digoxin renal clearance (treatment/control)

    Time frame: 0-48

    ratio of digoxin renal clearance in the presence to absence of gender-affirming estradiol treatment.

Secondary outcomes

  1. midazolam Cmax ratio (treatment/control)

    Time frame: 0-6 hours

    ratio of the maximum plasma concentration (Cmax) of midazolam in the presence to absence of gender-affirming estradiol treatment

Sponsors and collaborators

Lead sponsor

University of Washington

Other

Collaborators

  • National Institute of General Medical Sciences (NIGMS)

Registry information

Official study title

Effect of Gender-Affirming Estrogen Therapy on Drug Metabolism, Transport, and Gut Microbiota

Important dates

Study start
2022
Primary completion
2025
Study completion
2025
First posted
Jul 21, 2022
Registry last updated
Jan 9, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.