BROMOCRIPTINE SUPPRESSION OF PLASMA GROWTH HORMONE IN ACROMEGALY

Abstract

Acromegalic patients (12) were studied in 1 or more of 3 protocols to establish response of plasma growth hormone [human] (hGH) concentrations to a single oral test dose of bromocriptine, incremental dose therapy from 10-40 mg/day over 4 wk and sustained therapy with 20 mg/day over a 3 mo. period. Ten of the patients studied were previously treated by Y implantation, external pituitary irradiation or surgical hypophysectomy. A high incidence of side effects including postural hypotension, hallucinations and peripheral vasospasm was noted reducing the numbers of patients completing the 3 protocols. Suppression of hGH concentrations was disappointing; significant reductions in hGH concentrations occurred in 5 of 11 patients in response to a single test dose of bromocriptine and in only 1 of 7 patients treated with the drug over a sustained period. An impression of clinical improvement was gained in 1 patient, but there was no associated reduction in plasma hGH concentrations. Acromegalic patients who have failed to respond to conventional treatment apparently may be more resistant to bromocriptine therapy.