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NCT Number: NCT05488457

Oxytocin Pharmacokinetics and Pharmacodynamics

Oxytocin is the first-line drug to promote contraction of the uterus and prevent atony immediately after delivery. Nonetheless, unpredictable uterine atony refractory to oxytocin affects roughly 250,000 parturients annually in the U.S. and rates are increasing. This two-part study will measure the action of oxytocin at cesarean delivery. The first part will measure the pharmacokinetics of a single intravenous (IV) dose of deuterium-labeled oxytocin. The second part will measure the pharmacodynamics of all plasma oxytocin to see how concentrations correspond to the contractile effect on the uterus.

After delivery of the fetus, study subjects will receive a bolus of IV deuterated oxytocin followed by an unlabeled oxytocin infusion. Venous blood samples drawn at multiple time points (within 1 hour after delivery) will be analyzed for plasma concentrations of labeled and unlabeled (endogenous + exogenous infused) oxytocin over time. Plasma concentrations will be compared with 0-10 uterine tone scores measuring uterine contraction strength, to describe the concentration-effect relationship.

The goal of this study is to define both the pharmacokinetics and pharmacodynamics of oxytocin in parturients to help identify the cause(s) of failed first-line oxytocin therapy.

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Key information

Conditions

Post Partum Hemorrhage Blood Loss Cesarean Section Complications Female Urogenital Diseases and Pregnancy Complications Hemorrhage Obstetric Labor Complications Pathologic Processes Pathological Conditions, Signs and Symptoms Postpartum Hemorrhage Pregnancy Complications Puerperal Disorders Urogenital Diseases Uterine Hemorrhage

Age range

18 year–50 year

Sex eligibility

Female

Study type

Interventional

Phase

Phase 2

Primary location

Stanford University, Stanford, California, United States

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About this study

Parturients aged 18-50 with an intrauterine term pregnancy (37 weeks or greater) undergoing non-emergent cesarean delivery at the University of Chicago (UC) and Stanford University will be recruited.

Methods: All subjects will receive standard pre-, intra- and postoperative care for their cesarean delivery with additional study interventions.

Study subjects will have an additional intravenous (IV) catheter inserted for intra-operative study-related blood draws.

A single, 1 International Unit (IU) bolus of deuterated oxytocin (d5OT) will be given to the subject, followed by an infusion of standard protocol oxytocin immediately after placental delivery. IV samples will be drawn from the study IV at 0, 1, 2.5, 5, 10, 20, 30, 45, 60 minutes following administration of the study drug. The samples will be processed, batched and shipped to the central lab being used in this study. Uterine tone scores will be measured simultaneously with blood draws until accurate palpation is no longer possible. Uterine tone score is a 0 to 10 numeric rating scale with 0 to describe unsatisfactory or no uterine tone and 10 to describe perfect uterine tone.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • 18-50 years old
  • intrauterine pregnancy
  • term (>39 weeks gestation or 37-39 weeks gestation with fetal or maternal medical indication for delivery) pregnancy
  • non-emergent (scheduled or unscheduled) cesarean delivery

Exclusion criteria

  • allergy or contraindication to oxytocin
  • inability to provide informed consent

Treatment and study plan

deuterated oxytocin (d5OT)

Drug

Subjects will receive a 1 IU bolus of deuterated oxytocin (d5OT) intraoperatively during their nonemergent cesarean delivery.

Other names: Deuterium-labeled oxytocin

Primary outcomes

  1. Baseline plasma concentrations of deuterated oxytocin

    Time frame: Intraoperatively (prior to delivery)

    The plasma concentration of deuterium labelled oxytocin at baseline

  2. Plasma concentrations of deuterated oxytocin at 1 minute

    Time frame: Intraoperatively (1 minute following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 1 minute post-study drug

  3. Plasma concentrations of deuterated oxytocin at 2.5 minutes

    Time frame: Intraoperatively (2.5 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 2.5 minutes post-study drug

  4. Plasma concentrations of deuterated oxytocin at 5 minutes

    Time frame: Intraoperatively (5 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 5 minutes post-study drug

  5. Plasma concentrations of deuterated oxytocin at 10 minutes

    Time frame: Intraoperatively (10 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 10 minutes post-study drug

  6. Plasma concentrations of deuterated oxytocin at 15 minutes

    Time frame: Intraoperatively (15 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 15 minutes post-study drug

  7. Plasma concentrations of deuterated oxytocin at 20 minutes

    Time frame: Intraoperatively (20 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 20 minutes post-study drug

  8. Plasma concentrations of deuterated oxytocin at 30 minutes

    Time frame: Intraoperatively (30 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 30 minutes post-study drug

  9. Plasma concentrations of deuterated oxytocin at 45 minutes

    Time frame: Intraoperatively (45 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 45 minutes post-study drug

  10. Plasma concentrations of deuterated oxytocin at 60 minutes

    Time frame: Intraoperatively (60 minutes following study drug administration)

    The plasma concentration of deuterium labelled oxytocin at 60 minutes post-study drug

  11. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (at the time of study drug administration)

    Uterine tone will be ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  12. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (1 minute following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  13. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (2.5 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  14. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (5 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  15. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (10 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  16. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (15 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  17. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (20 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  18. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (30 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  19. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (45 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

  20. 0-10 Uterine Tone Score

    Time frame: Intraoperatively (60 minutes following study drug administration)

    Uterine tone ranked by the obstetrician on a 0-10 scale by palpation of the uterus. A score of 0 will represent 'no tone' and a score of 10 will represent 'perfect tone'. The relationship between plasma concentrations and clinical effect will be determined for pharmacodynamic modeling.

Study contacts

Contact information is provided by the study sponsor or research team.

Naida M Cole, MD

CONTACT

[email protected]

773-702-6700

Somayeh Mohammadi

CONTACT

[email protected]

17738343274

Sponsors and collaborators

Lead sponsor

University of Chicago

Other

Collaborators

  • Stanford University

Registry information

Official study title

Pharmacokinetics and Pharmacodynamics of Oxytocin in Cesarean Delivery

Important dates

Study start
2025
Primary completion
2026
Study completion
2027
First posted
Aug 4, 2022
Registry last updated
Jul 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.

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