Acute effect of octreotide, cabergoline and a combination of both drugs on GH secretion in acromegalic patients.

PURPOSE: The acute GH lowering effects of a single dose of either octreotide (OCT) or cabergoline (CAB), given alone and in combination, were studied in a series of 21 patients with acromegaly. PATIENTS AND METHODS: Plasma GH was measured for 8 hours after a single subcutaneous injection of OCT (100 micrograms) and for 48 hours after a single oral dose of CAB (0.5 mg) in all patients. Fourteen patients, who did not suppress GH levels below 5 micrograms/L after either OCT or CAB given alone, also received a combination of both drugs (OCT 100 micrograms s.c. + CAB 0.5 mg p.o. 24 h before OCT). RESULTS: GH levels were acutely suppressed by more than 50% in 15/21 cases after OCT alone and in 5/21 after CAB alone, respectively (P < 0.01). In the 14 patients who received the combined test, the magnitude of GH suppression was significantly higher than after OCT alone 4, 6 and 8 hours after OCT administration (P < 0.02). In patients with mixed GH/PRL-secreting tumors, the additive effect of OCT and CAB was observed at each time point. CONCLUSION: These results suggest that combined therapy with OCT and CAB may be more effective in suppressing GH secretion than either compound given alone, especially in patients with GH/PRL-secreting adenomas.