Inhibition of uterine contractility with various tocolytics with and without progesterone: In vitro studies

Abstract

Objective: Various tocolytics are used to suppress uterine contractility in patients in preterm labor. Progesterone (P4) is used in patients at high risk for preterm delivery. In this study, we evaluated the effects of various tocolytics with and without P4 to examine effects on uterine contractility. Study Design: Uterine tissues (n = 280) from women undergoing cesarean at term were exposed in vitro to various agents (vehicle, magnesium sulfate [MgSO 4], nifedipine, indomethacin, or pinacidilall with and without P4). Contractility was measured before and after addition of the various agents. Results: P4 alone at 105 mol/L concentration has little effect to inhibit contractility (P .05). Nifedipine (108 mol/L) and indomethacin (105 mol/L) inhibit contractions alone (P