Effects of the Dopamine Agonist CV 205–502 in Human Prolactinomas Resistant to Bromocriptine

Abstract

In 21 patients with prolactinomas resistant to bromocriptine, we studied the effects of CV 205-502 on PRL hypersecretion and tumor mass, as assessed by consecutive computed tomography examinations. Cell culture studies were performed in 9 of such tumors. In 11 patients (group I; 52%) with a mean baseline plasma PRL level of 468 +/- 160 micrograms/L (+/- SE), normal PRL values were achieved after 1-6 months of treatment with 0.1-0.5 mg/day CV 205-502. Tumor size was reduced by 25% or more in 6 of 11 patients. In group II (n = 10), PRL levels (948 +/- 538 micrograms/L at baseline) were reduced by 48% after treatment with 0.1 mg/day CV 205-502. A progressive increase in the daily dose up to 0.5 mg did not further improve the partial reduction of PRL. No reduction in tumor size was observed in this group. The cell culture studies showed that 1) a brief exposure to both drugs provoked PRL suppression lasting 3 days; 2) in group I, CV 205-502 suppressed PRL release more efficiently than bromocriptine, with a ma...