TREATMENT OF MACROPROLACTINOMA WITH THE NEW POTENT NONERGOT D2-DOPAMINE AGONIST QUINAGOLIDE AND EFFECTS ON PROLACTIN LEVELS, PITUITARY-FUNCTION, AND THE RENIN-ALDOSTERONE SYSTEM - RESULTS OF A CLINICAL LONG-TERM STUDY

The oral non-ergot D2-dopamine agonist quinagolide (CV205-502, CAS 870 56-78-8) has proven to be highly effective in suppressing elevated pro lactin (PRL) levels. It was the aim of this study to search for possib le interference of the drug with other endocrine systems which are par tly under dopaminergic control, and to compare such effects to those o f previously investigated prolactin inhibitors. Twelve patients suffer ing from macroprolactinoma were treated for at least 6 months with dai ly doses ranging from 50 up to 300 mug During the first two months, in dividual doses were gradually increased either until serum PRL levels reached the normal range (n = 7) or until side effects made a further dose increase intolerable (n = 5). Mean basal PRL levels fell from 255 +/- 65 (SEM) ng/ml before treatment to 19 +/- 8 ng/ml, after the defi nite dose was reached (p < 0.01). Luteinizing hormone (LH) rose from 0 . 6 +/- 0. 8 (SD) to 1.7 +/- 1.6 mU/ml (p < 0.05). While basal levels of aldosterone, renin, follicle-stimulating hormone (FSH), triiodothyr onine (T3), testosterone, and estradiol in females were not affected b y the treatment, we found a significant rise in thyroxine (T4) and a d ecrease of estradiol in males. Blood pressure and renal clearances of creatinine, sodium, potassium, and chloride failed to show any signifi cant change. Following stimulation with metoclopramide, aldosterone an d renin rose sharply before treatment was initiated When the test was repeated during treatment, the increase of plasma renin was slightly d ampened, whereas the rise of aldosterone remained unaffected The respo nse of thyrotropin (TSH), LH and FSH to stimulation with thyrotropin-r eleasing hormone (TRH) and luteinizing hormone-releasing hormone (LHRH ) dit not change during quinagolide treatment. It is concluded that qu inagolide long-term treatment does not affect hormonal systems other t han prolactin in a clinically relevant way.