Selective and extremely long inhibition of prolactin release in man by 1-ethyl-3-(3'-dimethylaminopropyl)-3-(6'-allylergoline-8'-beta- carbonyl)-urea-diphosphate (FCE 21336).

The effects on anterior pituitary function of FCE 21336 (1-ethyl-3-(3'-dimethylaminopropyl)-3-(6'-allylergoline-8'-beta-ca rbonyl)-urea- diphosphate), a synthetic ergoline derivative with selective dopamine agonistic properties, were studied. Circulating PRL, GH, TSH, cortisol and LH levels were determined up to 96 h after single oral doses of 50, 100, 200 and 300 micrograms of the compound to eight healthy males, and up to 168 h after single oral doses of 400 and 600 micrograms to six healthy males, according to double-blind, within subjects, experimental designs vs placebo. Vital signs, ECG, laboratory tests and the appearance of newly observed signs and symptoms were monitored. A dose-related decrease of serum PRL in comparison with both basal and post-placebo levels was observed after 200 micrograms and greater doses of the compound, with inhibition of spontaneous circadian rhythm. Maximal inhibition (PRL less than 2 ng ml-1) was observed in one out of five subjects after 200, three out of seven subjects after 300, four out of six after 400 and five out of six subjects after 600 micrograms. The effect was of rapid onset and long duration; the maximum or nearly maximum decrease was observed within 3 h after dosing as well as up to 96 h (200 and 300 micrograms) and up to 168 h (400 and 600 micrograms). No modifications of GH, TSH, LH and cortisol as well as of vital signs, ECG and laboratory tests were apparent.(ABSTRACT TRUNCATED AT 250 WORDS)