Prolactin-lowering effect of acute and once weekly repetitive oral administration of cabergoline at two dose levels in hyperprolactinemic patients

To further evaluate the potency and time course of the PRL-lowering effect of single oral doses of cabergoline, two doses of the drug were given to 51 hyperprolactinemic patients who also received 2.5 mg bromocriptine according to a randomized cross-over design. One group (n = 26) received 0.3 mg, and the other (n = 25) received 0.6 mg. Both cabergoline doses induced a significant fall in serum PRL levels, which lasted, on the average, from 3 h to 5 days after 0.3 mg and from 3 h to 14 days after 0.6 mg; the mean maximum decrease after 0.3 mg was -65 ± 4% (±SEM), significantly (P <0.05) less than that after bromocriptine (group mean, -73 ± 4%), and it was -76 ± 3% after 0.6 mg, not significantly different from that induced by bromocriptine (group mean, -71 ± 4%). The effect of 0.6 mg cabergoline was significantly greater than that of 0.3 mg (P <0.01). In a second study designed to evaluate the possible therapeutic use of the new drug, 0.3 or 0.6 mg cabergoline was administered orally once weekly for 8 weeks to 2 groups of 15 and 16 hyperprolactinemic patients, respectively. Serum PRL levels fell significantly by the first week and reached a plateau after 2 doses in the 0.6 mg cabergoline-treated group and after 5 doses in the 0.3 mg-treated group; the absolute PRL decrease was greater in the former. Ten patients in each group achieved normal serum PRL levels, and a marked decrease (>50% of pretreatment values) occurred in all patients treated with 0.6 mg and in 13 treated with 0.3 mg weekly. Resumption of menses occurred during the treatment period in 15 of the 17 premenopausal women with amenorrhea. Six patients who had poor responses had better responses when given higher drug doses for 4 weeks, and serum PRL levels became normal in the 3 receiving 0.6 mg twice weekly. These data confirm that cabergoline is a long-acting oral dopaminergic drug and suggest that it may be a useful agent for the treatment of patients with hyperprolactinemia.