Bromocriptine therapy in acromegaly. A long-term review of 35 cases.

Bromocriptine (CB-154, Parlodel, Sandoz) was given to 35 acromegalic patients for a period of 6-36 months. Basal and post-therapy endocrine functions including estimation of serum growth hormone (GH) profile; and GH kinetics during oral glucose tolerance test, augmented insulin tolerance test and thyrotrophin releasing hormone test were determined. The pituitary tumour size was delineated by a pneumoencephalogram. The mean GH levels ranged from 14 micrograms/l to 316 micrograms/l. Bromocriptine suppressed GH values to 5 micrograms/l or less in 16 patients and less than 10 micrograms/l in a further 6 patients. In 33 patients GH values fell to 50% of the basal value or less. There was no significant GH reduction in 2 'nonresponders'. Bromocriptine did not block the stress-induced GH secretion. It did not disturb pituitary functions other than prolactin which was suppressed much earlier and was maintained with smaller doses. GH suppression on the other hand was shortlived and rebounded when the drug was omitted. It had no adverse effect on tumour size in 2 patients having suprasellar extension of the tumour. Bromocriptine improved carbohydrate tolerance and sexual function although it did not affect insulin and gonadotrophin values. It seems reasonable to offer a trial of bromocriptine in all patients with acromegaly where therapy is deemed necessary as it is well tolerated, has insignificant side effects and no adverse drug interactions. Its high cost and prolonged course are obvious disadvantages. Caution should be exercised in cases with suprasellar extension and visual field involvement.