摘要
Treatment with antiprogestins ru 486,zk98.734 or ZK98.299 during the early or mid luteal phase induces premature menstruation and decrease in circulating progesterone levels in bonnet monkeys zk98.734 is a more potent luteolytic agent as compared with ru 486.the luteolytic effects are primarily due to the blockade of gonadotropin release rather than a direct effect on the ovary treatment with a single s.c.dose of ru 486during the early luteal phase or during the periimplantation period prevents pregnancy in bonner monkeys none of the 20 animals treated with different dose of ru 48+(5,10 or 20 mg)became pregnant whereas out of eight animals in the control group three became pregnant in one cycle of exposure this antinidatory action of RU 486 is due to its luteolytic effects as well as inhibitory, effects on the endometrial development. Since the treatment also caused shortening of the menstrual cycle length,this approach in the present dosage.form can only be used as an ernergency method of contraception. However. it may he possible to titrate the dose of antiprogestion which may alter the endometrial receptivity to the blustcyst without disturbing the normalmenstrual cycle rhythm.
