Objective: To evaluate a possible effect of Mifepristone on amniotic fluid volume in near term pregnant macaque monkeys.
Study design: Six pregnant near term monkeys (144 +/- 11 days of gestation) were either treated 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 placebo (t0h) and 24 h later (t24h).
Results: Amniotic fluid volume (AFV) measured at t0h 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 t24h when compared to AFV at t0h in placebo-treated (88 +/- 31 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 ratio of AFV (t24h/t0h) was found to be significantly lower in Mifepristone-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 antiprogestin on AFV.
Conclusion: In near term macaque monkeys, Mifepristone at 10 mg/kg induces a significant decrease of amniotic fluid volume within 24 h.