Tocolytic and cardiovascular effects of the calcium antagonist diltiazem in the near-term pregnant rabbit.
Parturition was induced with a 1 U intravenous bolus dose of oxytocin in two groups of near-term pregnant rabbits chronically prepared with distal aortic catheters. One group (n = 7) received an intravenous infusion of diltiazem (270 micrograms/kg/min) and the other (n = 7) received saline solution. Parturition was markedly inhibited in the diltiazem-treated group, based on the time to delivery of the first and subsequent fetuses and the number of fetuses undelivered at the end of each study. A significant decline in maternal blood pressure was observed in the diltiazem-treated group, but no significant change in maternal heart rate occurred. These findings suggest that diltiazem may provide significant tocolysis without the reflex tachycardia that has been observed with other calcium antagonists. Further evaluation of the maternal and fetal cardiovascular effects of diltiazem as well as the establishment of lower effective tocolytic doses are warranted.
Department of Gynecology and Obstetrics, Stanford University School of Medicine, CA 94305.
R H
RH
Holbrook
R N
RN
Gibson
E M
EM
Voss
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004110:Diltiazem / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007743:Labor, Obstetric / Q000187:drug effects; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects* / Q000502:physiology; D011817:Rabbits; D014590:Uterine Contraction / Q000187:drug effects*
D004110:Diltiazem