17 alpha-hydroxyprogesterone caproate vehicle, castor oil, enhances the contractile effect of oxytocin in human myometrium in pregnancy.
OBJECTIVE
The possibility exists that the vehicle for 17-alpha-hydroxyprogesterone caproate, castor oil, exerts an effect on human uterine contractility. The aim of this study was to evaluate its effects on contractility of myometrial preparations that were obtained during pregnancy.


METHODS
Myometrial strips were suspended under isometric conditions. Contractility was induced with oxytocin. Strips were incubated in castor oil or physiologic salt solution and suspended for a further oxytocin challenge. Contractile integrals were compared between both groups.


RESULTS
Strips that were exposed to castor oil demonstrated increased contractile activity that was elicited by oxytocin (mean contractility value, 165.53%+/-17.03%; n=8; P=.004), compared with control strips (mean contractility value, 72.57%+/-7.48%; n=8; P=.003). There was a significant increase in contractile activity of the castor oil-exposed strips, compared with those that were exposed to physiologic salt solution (n=8; P<.001).


CONCLUSIONS
Exposure of human myometrial preparations to castor oil results in enhanced oxytocin-induced contractility.
O'Sullivan
Michael D
MD
Department of Obstetrics and Gynaecology, Clinical Science Institute, National University of Ireland Galway, Galway University Hospitals, Newcastle Road, Galway, Ireland.
Hehir
Mark P
MP
O'Brien
Yvonne M
YM
Morrison
John J
JJ
D019326:17-alpha-Hydroxyprogesterone / Q000008:administration & dosage*; D000328:Adult; D002368:Castor Oil / Q000008:administration & dosage*; D004357:Drug Synergism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007273:Injections, Intramuscular; D010121:Oxytocin / Q000502:physiology*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third / Q000502:physiology; D014590:Uterine Contraction / Q000187:drug effects* / Q000502:physiology*
D010121:Oxytocin; D019326:17-alpha-Hydroxyprogesterone; D002368:Castor Oil