Effects of the dopamine agonist CV 205-502 in human prolactinomas resistant to bromocriptine.
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 maximal inhibition of 72% at 10(-9) mol/L; and 3) in group II, CV 205-502 only achieved a 26% inhibition of PRL release at 10(-8) mol/L, superimposable to that of bromocriptine. These data indicate that in at least half of such adenomas resistant to bromocriptine, CV 205-502, probably due to its higher affinity toward the D2 dopamine receptor, can overcome such resistance.
Service d'Endocrinologie, Hôpital Nord, Marseille, France.
T
T
Brue
I
I
Pellegrini
G
G
Gunz
I
I
Morange
D
D
Dewailly
J
J
Brownell
A
A
Enjalbert
P
P
Jaquet
D000328:Adult; D000634:Aminoquinolines / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001971:Bromocriptine / Q000494:pharmacology / Q000627:therapeutic use*; D015259:Dopamine Agents / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000378:metabolism; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D015175:Prolactinoma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000378:metabolism; D014057:Tomography, X-Ray Computed; D014284:Triiodothyronine / Q000627:therapeutic use; D014407:Tumor Cells, Cultured
D000634:Aminoquinolines; D000970:Antineoplastic Agents; D015259:Dopamine Agents; D014284:Triiodothyronine; D001971:Bromocriptine; C046650:quinagolide; D011388:Prolactin; D007986:Luteinizing Hormone; D013006:Growth Hormone