Potent and selective somatostatin sst5 receptor agonist. Ki values are 0.4, 3.3, 52, 64 and 82 nM for cloned human sst5, sst1, sst2, sst3 and sst4 receptors respectively. Inhibits growth hormone release from rat pituitary cells (EC50 = 3.1 nM) and insulin release from mouse pancreatic islets (EC50 = 0.3 nM) in vitro.