Effects of combination therapy: somatostatin analogues and dopamine agonists on GH and IGF1 levels in acromegaly

BACKGROUND AND AIMS: Acromegaly is a complex endocrine disorder caused by excessive secretion of GH, secondary to a GH secreting pituitary adenoma or a mixed pituitary adenoma secreting GH and PRL. METHODS: The aim of this study was to evaluate the effects of combination therapy: dopamine agonist and somatostatin analogue on GH and IGF1 levels in a group of 30 patients with acromegaly. Cabergoline in a dose of 2 mg/week and 4 mg/week respectively was associated with Sandostatin LAR in a dose of 20 mg/month and 30 mg/months respectively. Eight patients were treated with Lanreotide 30 mg/week and Cabergoline 2 mg/week and 3 patients were treated with Bromocriptine 10 mg/day and Sandostatin LAR 30 mg/month. RESULTS: Combination therapy: Cabergoline and Sandostatin achieved normal levels of IGF1 in 32% of the patients, better results being obtained after 12 months of treatment in the group treated with 4 mg Cabergoline/week. In 37% of cases the levels of IGF1 decreased by 50% after 12 months of treatment. In the group treated with Cabergoline and Somatuline a normal level of IGF1 was achieved in 25% of patients after 12 months of treatment. The outcome for the group treated with Sandostatin and Bromocriptine was similar to that obtained under Cabergoline 2 mg/week. There was no significant correlation between the level of GH and the type or dose of dopamine agonist used. CONCLUSIONS: In conclusion, combination therapy consisting of dopamine agonist and somatostatin analogue achieves a significant reduction of IGF1 levels in patients with mixed adenomas secreting GH and PRL. A decrease in IGF1 levels is directly correlated with the dose of Cabergoline used.