Abstract
OBJECTIVE: Our purpose was to determine the relationship among plasma oxytocin levels, metabolic
clearance rate of oxytocin, and uterine activity in gravid women undergoing labor
induction. STUDY DESIGN: Ten women receiving oxytocin for labor induction and agreeing to participate had
blood sampled before initiation of oxytocin and at different levels of uterine pressure.
Samples were analyzed with 200 μl extracts from 1 ml of plasma with an oxytocin radioimmunoassay.
The intraassay coefficient of variation was <3%. Sensitivity of the assay was 1.5
pg/ml. Pharmacokinetic parameters including plasma levels and metabolic clearance
rates were calculated. Data were analyzed with the paired t test and linear and logistic regression. RESULTS: Mean oxytocin levels and metabolic clearance rates were 26.6 pg/ml and 7.97 ml/min.
There was no correlation between changes in oxytocin level and metabolic clearance
rate. Increases in infusion rates were correlated with increases in oxytocin levels
(r = 0.71, p < 0.001). Cervical dilatation and uterine contraction pressures did not correlate
with oxytocin levels. CONCLUSION: Peripheral plasma levels of oxytocin may not accurately reflect uterine activity
or progress in labor. Plasma levels of oxytocin may merely reflect the rate of oxytocin
infusion. (AM J OBSTET GYNECOL 1996;174:1590-3.)
Keywords
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Article Info
Publication History
Accepted:
October 10,
1995
Received in revised form:
October 2,
1995
Received:
May 15,
1995
Footnotes
☆From the Department of Obstetrics and Gynecologyaand the Clinical Investigation Directorate,bWilford Hall Medical Center.
☆☆Reprint requests: Andrew J. Satin, MD, Wilford Hall Medical Center/PSO, 2200 Bergquist Dr., Suite 1, Lackland AFB, TX 78236-5300.
★6/1/69802
Identification
Copyright
© 1996 Published by Elsevier Inc.
