Effect of antiprogestin, hCG and a prostaglandin analogue on human uterine contractility

Abstract

In the present study, the effect of hCG and RU 486 on non-pregnant uterine contractility and the sensitivity of the myometrium to the prostaglandin analogue misoprostol (GD Searle, Chicago, IL, USA) was evaluated. Seven healthy female volunteers participated in the study. Uterine contractility was recorded on cycle day LH+13 in two cycles. After recording the spontaneous contractility, 200 μg and 400 μg of misoprostol were administered orally at an interval of 45–60 minutes. In the second month, 5,000 IU hCG was administered on cycle day LH+8 and 10,000 hCG on cycle days LH+10 and LH+12, and 200 mg RU 486 on cycle day LH+11,48 hours prior to the recording. In three women, a third month was included in which the same treatment, except for RU 486, was given. Treatment with hCG delayed menstrual bleeding and resulted in a significant increase in the concentration of plasma progesterone. Following hCG, the degree of uterine contractility was reduced, while after hCG and RU 486 the uterus was significantly more active. In the control cycle and following hCG alone, misoprostol had a slight stimulatory effect. When RU 486 was added, the degree of contractility following misoprostol was 4 to 9 times greater than that found if RU 486 was not given. Late luteal administration of RU 486 is not an effective method of fertility regulation. The results of the present study indicate that a combination of RU 486 and misoprostol will be more suitable for this purpose.