1. The biochemical specificity and duration of action of a single 5 mg subcutaneous dose of des-AA1,2,4,5,12,13-d-Trp8-somatostatin were evaluated in eight patients with symptomatic pancreatic endocrine tumours.
2. There was a reduction by more than 50% for at least 10 h in plasma concentrations of growth hormone, glucagon, gastrin and motilin and for 4–5 h in plasma insulin, pancreatic polypeptide, gastric inhibitory polypeptide and enteroglucagon.
3. This study shows that this octapeptide analogue of somatostatin, like somatostatin itself, lacks specificity in the hormones it suppresses. However, its prolonged duration of action against several hormones when given subcutaneously suggests that it may be of therapeutic use in a number of disease states where excessive plasma concentrations of one or more of these hormones occur.