Effect of methylergobasine maleate on serum gonadotrophin and prolactin in humans.

Intramuscular injection of 0.2 mg methylergobasine maleate3) (Methergin, Sandoz) in women on day 3 post-partum, in regularly menstruating women and in adult men, is followed within 30 to 75 min by a 50% decrease in serum prolactin concentration: the levels remain low until 180 min and increase between 180 and 240 min. The amplitude of the decrease is the same when prolactin is measured in terms of the same serum prolactin standard by a homologous ovine assay and by a homologous human assay. However, in the case of regularly menstruating women and of men serum prolactin concentration is some three times higher when estimated by the ovine assay than when estimated by the human assay. This difference between assay results obtained by the two radioimmunoassay methods could be due to heterogeneity of serum prolactin. However, non-specific effects of serum are not excluded. In regularly menstruating women and in men, intramuscular injection of 0.2 mg methylergobasine maleate is followed within 45 to 75 min by a 50% decrease in immunoreactive serum LH concentration without concomtant change in immunoreactive FSH. The depression of LH secretion lasts for 1 to 2 h. The circulating levels of HCG in post-partum women are not modified after intramuscular injection of Methergin. In humans as in animals and in in vitro studies, inhibition of prolactin and LH release induced by ergot drugs are likely due to both an indirect effect via the hypothalamus and to a direct effect on the pituitary cells.

Induced prolactin release in women under long-term medroxyprogesterone acetate treatment.

Medroxyprogesterone acetate (MPA) was administered, as a contraceptive, by intramuscular injection in doses of 150 mg every 90 days, or 300-450 mg every 180 days, to 5 women, over a period of 27 to 42 months. No major adverse reactions were reported, and the minor side effects were only as frequent as those reported for oral contraceptives. The LH basal levels were depressed in all subjects;; FSH and prolactin serum concentrations were within the range found in normally cycling women. Synthetic TRH released prolactin in 4 subjects, and the maximal response was within 10-20 minutes after TRH injection. In the fifth case there was no prolactin release.