Pergolide, a potent long-acting dopamine-receptor agonist.

After single doses (100 to 400 microgram orally), pergolide, a synthetic ergot, reduced basal plasma prolactin levels in normal subjects in a dose-related manner. This effect persisted for more than 24 hr. Multiple doses of pergolide (150 to 250 microgram daily for 7 days) resulted in a plasma prolactin decrease of more than 80%. A single dose of pergolide (150 microgram orally) suppressed plasma prolactin and abolished the plasma prolactin diurnal rhythm, i.e., suppression of sleep-induced elevation in plasma prolactin during a 40-hr period. Perphenazine (5 mg intramuscularly)-induced plasma prolactin elevation was inhibited by pergolide; the effect was dose dependent. After single or multiple doses, pergolide had no effect on plasma follicle-stimulating hormone, luteinizing hormone, cortisol, growth hormone, and thyroid-stimulating hormone. Pergolide appears to have specificity at the pituitary level for the dopamine receptors that mediate prolactin secretion.