Endocrine Abstracts

Cabergoline (CB) is a potent, long-acting dopamine agonist licensed for the treatment of hyperprolactinaemia and, although unlicensed, is extensively used to treat acromegaly. There is a dearth of data on the use of CB in the treatment of acromegaly. We have performed a retrospective analysis of CB therapy in 34 [19 male, mean age 46 years (range 14-82)22 macroadenomas] patients with acromegaly treated since 1975. The patients were divided into two groups, those on CB as sole therapy ('sole', n=28) and those on a fixed dose somatostatin analogue ('SSA', n=6) to which CB was added. The goals of therapy were a mean GH <5 milliunits per litre and IGF-1 <30 nanomoles per litre. In the 'sole' group (mean dose 2.5 g weekly, range 0.5-7.0) mean GH fell from 13.7 milliunits per litre (range 1.2-97.9) to 6.6 (1.0-30.9 P <0.001) with 33% of patients achieving a mean GH <5 mU\/l. Serum IGF-I fell from 58.3 nanomoles per litre (25.7-144.7) to 44.4 (11.3-92.3, P <0.001) and normalised in 20%. In the SSA patients (mean dose 3.6 g/week, range 1.0-7.0) mean GH fell from 28.6 mU/l (range 4.7-98.9) to 11.0 (1.7-21.1, P <0.005) with 20% of patients achieving a mean GH <5 milliunits per litre. Serum IGF-I fell from 80.9 nanomoles per litre (26.6-116.9) to 58.4 (7.7-99.6, P not significant) but did not normalize in any patients. Five patients discontinued CB due to nausea/dizziness/low mood, and 3 required a dose reduction. In conclusion, CB is a well-tolerated treatment of acromegaly capable of controlling GH secretion in a significant minority of patients. The dose of CB was sub-optimal and greater efficacy may be achieved with larger doses. There is a need for prospective dose titration studies.