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

Not yet recruiting

Conditions

Intervention / Treatment

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

Observational

Enrollment (Estimated)

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 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

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
Intervention / Treatment
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

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

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

Baylor Research Institute

Collaborators

University of Washington
Children's Hospital Medical Center, Cincinnati

Investigators

  • 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)

May 31, 2026

Primary Completion (Estimated)

February 1, 2028

Study Completion (Estimated)

March 1, 2028

Study Registration Dates

First Submitted

February 6, 2026

First Submitted That Met QC Criteria

February 12, 2026

First Posted (Actual)

February 19, 2026

Study Record Updates

Last Update Posted (Actual)

April 28, 2026

Last Update Submitted That Met QC Criteria

April 24, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Other Study ID 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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