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.
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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
PREVENTION
Masking
NONE
Enrollment
100
Subjects will receive a 1 IU bolus of deuterated oxytocin (d5OT) intraoperatively during their nonemergent cesarean delivery.
Stanford University
Stanford, California, United States
NOT_YET_RECRUITINGUniversity of Chicago
Chicago, Illinois, United States
RECRUITINGBaseline plasma concentrations of deuterated oxytocin
The plasma concentration of deuterium labelled oxytocin at baseline
Time frame: Intraoperatively (prior to delivery)
Plasma concentrations of deuterated oxytocin at 1 minute
The plasma concentration of deuterium labelled oxytocin at 1 minute post-study drug
Time frame: Intraoperatively (1 minute following study drug administration)
Plasma concentrations of deuterated oxytocin at 2.5 minutes
The plasma concentration of deuterium labelled oxytocin at 2.5 minutes post-study drug
Time frame: Intraoperatively (2.5 minutes following study drug administration)
Plasma concentrations of deuterated oxytocin at 5 minutes
The plasma concentration of deuterium labelled oxytocin at 5 minutes post-study drug
Time frame: Intraoperatively (5 minutes following study drug administration)
Plasma concentrations of deuterated oxytocin at 10 minutes
The plasma concentration of deuterium labelled oxytocin at 10 minutes post-study drug
Time frame: Intraoperatively (10 minutes following study drug administration)
Plasma concentrations of deuterated oxytocin at 15 minutes
The plasma concentration of deuterium labelled oxytocin at 15 minutes post-study drug
Time frame: Intraoperatively (15 minutes following study drug administration)
Plasma concentrations of deuterated oxytocin at 20 minutes
The plasma concentration of deuterium labelled oxytocin at 20 minutes post-study drug
Time frame: Intraoperatively (20 minutes following study drug administration)
Plasma concentrations of deuterated oxytocin at 30 minutes
The plasma concentration of deuterium labelled oxytocin at 30 minutes post-study drug
Time frame: Intraoperatively (30 minutes following study drug administration)
Plasma concentrations of deuterated oxytocin at 45 minutes
The plasma concentration of deuterium labelled oxytocin at 45 minutes post-study drug
Time frame: Intraoperatively (45 minutes following study drug administration)
Plasma concentrations of deuterated oxytocin at 60 minutes
The plasma concentration of deuterium labelled oxytocin at 60 minutes post-study drug
Time frame: Intraoperatively (60 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (at the time of study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (1 minute following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (2.5 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (5 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (10 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (15 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (20 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (30 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (45 minutes following study drug administration)
0-10 Uterine Tone Score
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.
Time frame: Intraoperatively (60 minutes following study drug administration)
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