Tacrolimus in Pregnancy

April 24, 2026 updated by: Baylor Research Institute

Optimization of Tacrolimus Management During Pregnancy: Modeling of Unbound and Whole Blood Tacrolimus in Pregnant Uterus Transplant Recipients

To create a formula that adjusts tacrolimus blood levels. This is needed because pregnant patients have higher levels of unbound tacrolimus. The adjusted formula will give a more accurate measure of the active drug in pregnant uterus transplant patients.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

A non-linear mixed effects model describing tacrolimus exposure in pregnant and non-pregnant subjects will be developed using prospectively collected de-identified data from pregnant uterus transplant recipients at BUMC.

The model will be analyzed to develop an estimating equation for tacrolimus unbound concentrations from whole blood concentrations, albumin and hematocrit during each trimester of pregnancy.

The estimating equation will then be applied to data from uterus transplant recipients enrolled in this study and retrospectively to uterus recipients transplanted since October 2020 to clinically validate the findings.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
55

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • Texas
      • Dallas, Texas, United States, 75246
        • Baylor University Center of Dallas

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

N/A

Sampling Method

Non-Probability Sample

Study Population

Uterus transplant recipient over 18 years of age receiving tacrolimus for immunosuppression.

Description

Inclusion Criteria:

  • Uterus transplant recipient
  • 18 to 50 years of age
  • receiving tacrolimus for immunosuppression.

Exclusion Criteria:

  • Individuals who have not had a uterine transplant
  • individuals over 50 years old

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Pregnant Individuals
Individuals who had a uterus transplant that are using tacrolimus during pregnancy.
Biological: Modeling of unbound and whole blood tacrolimus in pregnant uterus transplant recipients
Develop an estimating equation to correct tacrolimus whole blood concentrations given the known increase in the unbound tacrolimus concentration in pregnant patients to obtain a more accurate picture of active tacrolimus exposure (unbound drug) in pregnant uterus transplant recipients.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Understanding Tacrolimus Levels in Pregnancy
Time Frame: 2nd (weeks 13-26) and 3rd (weeks 27-40) trimester of pregnancy
Develop a joint non-linear mixed effect population pharmacokinetic model describing bound and unbound tacrolimus pharmacokinetics in pregnant subjects.
2nd (weeks 13-26) and 3rd (weeks 27-40) trimester of pregnancy

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Adjusting Tacrolimus Blood Levels by Trimester
Time Frame: 2nd (weeks 13-26) and 3rd (weeks 27-40) trimester of pregnancy
Create an equation to adjust whole blood tacrolimus concentrations for changes in drug binding during each trimester at the point of care
2nd (weeks 13-26) and 3rd (weeks 27-40) trimester of pregnancy
Linking the Mixed Pharmacokinetic Model and the Equation to Adjust Whold Blood Tacrolimus Concentrations to Active Tacrolimus Levels During and After Pregnancy
Time Frame: 1 week postpartum, 4 weeks, 5 weeks and 6 weeks postpartum
Correlate clinical outcomes with estimated unbound tacrolimus concentrations from uterus transplant recipients during each trimester and outside of pregnancy using whole blood trough concentrations and the model developed in Outcome 1
1 week postpartum, 4 weeks, 5 weeks and 6 weeks postpartum

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Baylor Research Institute

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University of Washington
Children's Hospital Medical Center, Cincinnati

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Nicole Wilson, Pharmacist, Baylor Scott and White Health

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

  • Organ Procurement and Transplantation Network (OPTN) and Scientific Registry of Transplant Recipients (SRTR). OPTN/SRTR 2023 Annual Data Report. U.S. Department of Health and Human Services, Health Resources and Services Administration; 2025.
  • Yo JH, Fields N, Li W, et al. Adverse Pregnancy Outcomes in Solid Organ Transplant Recipients: A Systematic Review and Meta-Analysis. JAMA Netw Open. 2024;7(8):e2430913.
  • Rodrigues-Diez R, González-Guerrero C, Ocaña-Salceda C, et al. Calcineurin inhibitors cyclosporine A and tacrolimus induce vascular inflammation and endothelial activation through TLR4 signaling. Sci Rep. 2016;6:27915.
  • Naesens M, Kuypers DRJ, Sarwal M. Calcineurin inhibitor nephrotoxicity. Clin J Am Soc Nephrol. 2009;4(2):481-508.
  • Zheng S, Easterling TR, Umans JG, et al. Pharmacokinetics of tacrolimus during pregnancy. Ther Drug Monit. 2012;34(6):660-670.
  • Schagen MR, Ulu AN, Francke MI, et al. Modelling changes in the pharmacokinetics of tacrolimus during pregnancy after kidney transplantation: A retrospective cohort study. Br J Clin Pharmacol. 2024;90(1):176-188.
  • Versluis J, Bourgonje AR, Touw DJ, et al. Pharmacokinetics of tacrolimus in pregnant solid-organ transplant recipients: a retrospective study. The Journal of Clinical Pharma. 2024;64(4):428-436.
  • Brännström M. A decade of human uterus transplantation. Acta Obstet Gynecol Scand. 2025;104(3):434-436.
  • Testa, G., McKenna, G. J., Gunby Jr, R. T., Anthony, T., Koon, E. C., Warren, A. M., Johannesson, L. (2018). First live birth after uterus transplantation in the United States. American Journal of Transplantation, 18(5), 1270-1274.
  • Wilson NK, Schulz P, Wall A, et al. Immunosuppression in uterus transplantation: experience from the dallas uterus transplant study. Transplantation. 2023;107(3):729-736.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 31, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 6, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 12, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 19, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 28, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 24, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 026-140

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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