A single-dose comparison of the acute effects between the new somatostatin analog SOM230 and octreotide in acromegalic patients

Treatment with the somatostatin receptor (sst) subtype 2 predominant analogs octreotide and lanreotide induces clinical and biochemical cure in approximately 65% of acromegalic patients. GH-secreting pituitary adenomas, which are not controlled, also express sst(5). We compared the acute effects of octreotide and SOM230, a new somatostatin analog with high affinity for sst(1,2,3,5) on hormone release in acromegalic patients. In a single-dose, proof-of-concept study, 100 mug octreotide and 100 and 250 mug SOM230 were given sc to 12 patients with active acromegaly. Doses of 100 and 250 mug SOM230 dose-dependently suppressed GH levels from 2-8 h after administration (-38+/-7.7 vs. -61+/-6.7%, respectively; P<0.01). A comparable suppression of GH levels by octreotide and 250 g SOM230 was observed in eight patients (-65 +/- 7 vs. -72 +/- 7%, respectively). In three patients, the acute GH-lowering effect of 250 mu g SOM230 was significantly superior to that of octreotide (-70 +/- 2 vs. -17 +/- 15%, respectively; P<0.01). In one patient, the GH-lowering effect of octreotide was better than that of SOM230. Tolerability for SOM230 was good. Glucose levels were initially slightly elevated after octreotide and SOM230, compared with control day, whereas insulin levels were only significantly suppressed by octreotide. We conclude that SOM230 is an effective GH-lowering drug in acromegalic patients with the potential to increase the number of patients controlled during long-term medical treatment.