[The antigonadrotropic activity of chlormadinone acetate in reproductive women]

Progesterone modulates pulsatile secretion of LH throughout the normal menstrual cycle in women. This effect is observed essentially at hypothalamic level via progesterone receptors, with a decline in frequency of GnRH cyclic secretion. It was observed that when several nor-progesterone and nor-testosterone derived progestins were administered, the antigonadotropic function of the hypothalamic-pituitary-ovarian axis was inhibited.

Determine chlormadinone acetate's antigonadotropic activity when administered according to two schemes: from the day 5 to day 25 (L5) and from day 8 to day 25 (L8) of the menstrual cycle.

Randomized monocentric study carried out in twenty normally cycling healthy women included in two parallel groups and receiving 10 mg of chlormadinone acetate once a day, either from day 5 to day 25, or from day 8 to day 25 of the menstrual cycle. Hormonal dosages were determined with blood samplings performed each day from day 5 to day 25 of each menstrual cycle for estradiol, FSH and LH and from day 14 to day 25 of each cycle for progesterone.

Sixteen women in group L5 and 14 in group L8 were kept for per protocol analysis. At the first cycle of treatment a decline in LH peak amplitude was observed in all women (16/16) of the L5 group and in 12 women out of 14 in the L8 group. For all women under treatment, graphs show a decrease in progesterone secretion parallel to decline in LH secretory peak amplitude as well as significant decline in estradiol secretion. Clinical tolerance was good.

Chlormadinone acetate induces anti-gonadotropic activity which is similar to other nor-progesterone and nor-testosterone derived progestins. This activity is shown at first cycle when the drug is used from day 5; when the drug is used from day 8, cycle 2 or 3 must be waited for in order to obtain the same result.