MIFEPRISTONE (RU-486) AND ITS INCIDENCE ON AMNIOTIC-FLUID VOLUME IN NEAR-TERM FETAL MACAQUE MONKEYS

Objective: To evaluate a possible effect of Mifepristone on amniotic f luid volume in near term pregnant macaque monkeys. Study design: Six p regnant near term monkeys (144 +/- 11 days of gestation) were either t reated intramuscularly by Mifepristone (10 mg/kg, n = 3) or a placebo (n = 3). Amniotic fluid volumes were measured by a dilution technique using blue Evans, just prior to the injection of Mifepristone or place bo (t(0h)) and 24 h later ((24h)). Results: Amniotic fluid volume (AFV ) measured at t(0h) was found to be statistically the same in placebo and Mifepristone-treated macaque monkeys (95 +/- 31 vs. 126 +/- 25 ml, respectively, P > 0.05). AFV was found to be lower at t(24h) when com pared to AFV at t(0h) in placebo-treated (88 +/- 131 vs. 95 +/- 31 ml, respectively, P < 0.05) and in Mifepristone-treated macaque monkeys ( 72 +/- 7 vs. 126 +/- 25 ml, respectively, P < 0.05). Moreover, the rat io of AFV (t(24h)/t(0h) was found to be significantly lower in Mifepri stone-treated monkeys when compared to the placebo group (57.9 /- 5.7% vs. 92.2 +/- 2.1%, P < 0.05) indicating a specific effect of the anti progestin on AFV. Conclusion: In near term macaque monkeys, Mifepristo ne at 10 mg/kg induces a significant decrease of amniotic fluid volume within 24 h.