# Somatostatin > The universal "off switch" — a cyclic hormone that inhibits growth hormone, insulin, glucagon, and gut secretions; its analog octreotide is the workhorse drug. - Also known as: SST, Somatotropin release-inhibiting factor, SRIF, GHIH, Octreotide (analog), Sandostatin - Class: Peptide Hormones, Growth Hormone - FDA approved: No - Canonical page: https://americanpeptide.com/catalog/somatostatin ## Overview Somatostatin is an inhibitory hormone with unusually broad reach: it suppresses the release of growth hormone, insulin, glucagon, gastrin, and a range of other pancreatic and gastrointestinal secretions. The endogenous 14-residue cyclic peptide has a half-life of only a couple of minutes, so the therapeutics that exploit its biology are stabilized analogs — octreotide (Sandostatin) and lanreotide — used for acromegaly and hormone-secreting neuroendocrine tumors. Somatostatin is the body’s general inhibitory signal in the endocrine system. Discovered as the hypothalamic factor that blocks growth-hormone release (hence "growth-hormone-inhibiting hormone"), it turned out to be far more widely distributed — in pancreatic delta cells, throughout the gut, and in the nervous system — where it brakes the secretion of insulin, glucagon, gastrin, secretin, and more. It is the counterweight to the body’s many "go" signals. Its therapeutic problem is its virtue: it shuts off so much, so briefly. Native somatostatin is cleared within minutes, which makes the raw hormone impractical as a drug. The solution was engineering — octreotide is a synthetic eight-residue analog that keeps the essential receptor-binding core, resists degradation, and lasts long enough to dose. Long-acting depot formulations of octreotide and lanreotide now stretch that to monthly injections. Clinically these analogs are the standard medical therapy for acromegaly (growth-hormone excess) and for controlling the hormone-driven symptoms of neuroendocrine tumors such as carcinoid syndrome. The same broad inhibition also makes them useful in certain GI bleeding and secretory states. Somatostatin is the clearest example in this catalog of a hormone too short-lived to use directly, productively reborn as a stabilized analog. ## Mechanism Agonist at five somatostatin receptor subtypes (SSTR1–5), Gi-coupled, lowering cAMP and inhibiting hormone secretion across the pituitary, pancreatic islets, and GI tract. Octreotide is biased toward SSTR2/SSTR5, which carry the clinically useful growth-hormone- and tumor-suppressing effects. ## Chemistry | Property | Value | | --- | --- | | Molecular weight | 1637.9 Da | | CAS number | 38916-34-6 | ## Sequence ``` AGCKNFFWKTFTSC (3–14 disulfide) ``` ## Research areas Studied in: Acromegaly, Neuroendocrine tumors, Growth hormone regulation, Peptide hormones. Guides on this site: - [Growth Hormone & Body Composition](https://americanpeptide.com/research-areas/growth-hormone-axis): Secretagogues studied for GH release, IGF-1, and body composition. - [Peptide Hormone Synthesis](https://americanpeptide.com/research-areas/peptide-hormones): How hormone sequences are turned into pure, stable, manufacturable synthetic drugs. ## Key research - Acromegaly — somatostatin analogs (octreotide, lanreotide) are first-line medical therapy to suppress excess growth hormone and IGF-1. - Neuroendocrine tumors — control hormone-mediated symptoms (e.g. carcinoid syndrome) and can slow tumor progression; radiolabeled analogs also enable SSTR-targeted imaging and therapy. - Broad endocrine inhibition — suppresses GH, insulin, glucagon, gastrin and other GI/pancreatic secretions via SSTR1–5. - Analog engineering — octreotide distills the 14-residue hormone to a protease-resistant 8-residue peptide, the design that made the biology druggable. - Short native half-life — endogenous somatostatin lasts only minutes, the reason the raw hormone is not used as a chronic therapy. ## Storage, handling & synthesis **Synthesis.** A cyclic 14-mer requiring regioselective formation of the 3–14 disulfide after chain assembly. The native peptide is rarely the product worth making — its minutes-long half-life makes it impractical — so the synthetic target is octreotide: the 14-mer distilled to a protease-resistant 8-residue cyclic analog incorporating D-Phe and D-Trp and a reduced C-terminal threoninol. Those D-residue couplings and the controlled disulfide cyclization are the hard steps, and they are exactly what stretch the half-life from minutes to hours. A defining case of pharmacophore minimization in peptide drug design. ## FAQs ### What is somatostatin? A cyclic peptide hormone that broadly inhibits secretion — of growth hormone, insulin, glucagon, and many gut hormones. It acts as a general "off switch" across the endocrine and digestive systems. ### Why is octreotide used instead of somatostatin itself? Native somatostatin is cleared within minutes, too briefly to be a practical drug. Octreotide is a stabilized synthetic analog that keeps the key receptor-binding region but resists breakdown, so it can be dosed and even formulated as a long-acting depot. ### What is it used to treat? Its analogs are standard therapy for acromegaly and for controlling hormone-related symptoms of neuroendocrine tumors such as carcinoid syndrome. This page is a research and educational reference, not treatment guidance. ### Is this medical advice? No — this is a research and educational reference, not dosing guidance. ## Latest research Recent trials and publications mentioning Somatostatin, pulled automatically from ClinicalTrials.gov and PubMed (unfiltered search results, refreshed daily). ### Recent trials - [177Lu-DOTA-EB-TATE in Adult Patients With Metastatic, Radioactive Iodine Non-Responsive Oncocytic (Hurthle-Cell) Thyroid Cancer](https://clinicaltrials.gov/study/NCT06991738) — NOT_YET_RECRUITING · PHASE1, PHASE2 · NCT06991738 - [Testing Lutetium Lu 177 Dotatate in Patients With Somatostatin Receptor Positive Advanced Bronchial Neuroendocrine Tumors](https://clinicaltrials.gov/study/NCT04665739) — RECRUITING · PHASE2 · NCT04665739 - [RYZ101 for the Treatment of Progressive or Recurrent Intracranial Meningioma](https://clinicaltrials.gov/study/NCT07150806) — RECRUITING · PHASE1, PHASE2 · NCT07150806 - [Lu-177-DOTATATE (Lutathera) in Combination With Olaparib in Inoperable Gastroenteropancreatico Neuroendocrine Tumors (GEP-NET)](https://clinicaltrials.gov/study/NCT04086485) — RECRUITING · PHASE1, PHASE2 · NCT04086485 - [ALXN2420 Versus Placebo in Combination With Somatostatin Analogs in Participants With Acromegaly](https://clinicaltrials.gov/study/NCT07037420) — TERMINATED · PHASE2 · NCT07037420 - [Efficacy and Safety of 177Lu-edotreotide PRRT in GEP-NET Patients](https://clinicaltrials.gov/study/NCT03049189) — ACTIVE_NOT_RECRUITING · PHASE3 · NCT03049189 --- Source: AmericanPeptide.com — https://americanpeptide.com/catalog/somatostatin Data license: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Attribution: AmericanPeptide.com. Research reference only — computational and educational content, not medical advice.