Somatostatin Analogue
A synthetic peptide that mimics the inhibitory effects of natural somatostatin, suppressing the release of growth hormone, insulin, glucagon, and gastrointestinal peptides. Octreotide, lanreotide, and pasireotide are approved somatostatin analogues used to treat acromegaly and neuroendocrine tumours.
Technical Context
Natural somatostatin (SRIF-14 and SRIF-28) acts on five receptor subtypes (SSTR1-5). Its half-life of 1-3 minutes makes it therapeutically impractical. Synthetic analogues are truncated and stabilised: octreotide (8 aa, cyclic) and lanreotide (8 aa, cyclic) are selective for SSTR2 and SSTR5 — the subtypes most relevant to GH-secreting and NET tumour cells. Pasireotide (6 aa, cyclic) binds SSTR1, 2, 3, and 5, with particular affinity for SSTR5, which is highly expressed on corticotroph adenomas (Cushing's disease). Long-acting formulations include octreotide LAR (PLGA microspheres, monthly IM), lanreotide autogel (self-assembling nanotubes, monthly deep SC), and pasireotide LAR (microspheres, monthly IM).