What it is
Somatostatin is a hormone the body makes to switch other hormones off. It comes in two lengths, both cut from one precursor protein:
| Form | Length | Position in the 116-residue precursor (UniProt P61278) |
|---|---|---|
| Somatostatin-14 | 14 amino acids | 103–116 |
| Somatostatin-28 | 28 amino acids | 89–116 |
The short form's sequence is AGCKNFFWKTFTSC. The two cysteines, at positions 3 and 14, are joined by a disulfide bond, so the peptide forms a ring. The same precursor carries a third, separate peptide further along its chain — neuronostatin, residues 31–43 — which UniProt annotates as able to add to somatostatin's effect on growth hormone.
The human evidence here is physiology — how the hormone behaves in people — not trials of a product: no approved product of somatostatin itself exists in the United States.
How it was found
In 1973 a team led by Paul Brazeau and Roger Guillemin reported in Science a peptide from sheep hypothalamus that, at a concentration of 1 × 10⁻⁹ M, stopped rat and human pituitary cells releasing growth hormone, and did the same in live rats. The paper gave its full structure — the 14 amino acids above — and showed that a synthetic copy worked (PMID 4682131). It was named for that finding: somatotropin (growth hormone) plus statin (stopping).
What it does
UniProt's summary of the literature lists what it inhibits from the pituitary: growth hormone, prolactin, ACTH, luteinizing hormone and TSH. It also dampens the growth-hormone surge that ghrelin would otherwise cause. Outside the brain it is made in the gut and the pancreas, where it suppresses digestive and metabolic hormones. The labels of its two drug copies, which describe them as acting like the natural hormone, give the list: the octreotide label names serotonin, gastrin, VIP, secretin, motilin, pancreatic polypeptide, insulin and glucagon; the lanreotide label adds cholecystokinin and reports no significant effect on secretin.
Why the drugs are copies, not the hormone
Every somatostatin medicine approved in the United States is an analogue: openFDA returns no application with somatostatin itself as the active ingredient (2026-09-30). The copies keep the part of the ring that binds the receptor and change the rest:
| Length | Structure | First US approval | |
|---|---|---|---|
| Somatostatin-14 | 14 | Ring closed at 3–14; all natural amino acids | — |
| Octreotide | 8 | Ring; D-phenylalanine and D-tryptophan; threoninol end | 1988 |
| Lanreotide | 8 | Ring; D-naphthylalanine and D-tryptophan; threoninamide end | 2007 |
The mirror-image (D) amino acids and capped ends are the standard ways of making a peptide harder for the body's enzymes to cut. What that bought is visible on the labels: the lanreotide label reports a half-life of 23 to 30 days for its monthly depot, and octreotide became the first somatostatin drug that could be swallowed, as a capsule, in 2020.
Where it stands
Somatostatin is a subject of research, not a product. PubMed indexes 39,712 records for it, 852 of them tagged as randomised controlled trials (2026-09-30) — one of the largest literatures of any entry in this library, and most of it concerns the hormone's physiology and the drugs built on it. It is not sold as a research peptide in the way many entries here are.
Related reading
The hormones somatostatin holds back are the ones that growth-hormone releasers such as tesamorelin and ipamorelin push up. VIP is one of the gut hormones its analogues suppress, and glucagon and insulin are both under its control in the pancreas.