Somatostatin
Also known as: somatotropin release-inhibiting factor (SRIF), growth hormone release-inhibiting hormone (GHRIH), somatostatin-14, somatostatin-28, SS-14, SS-28, SRIF-14, SRIF-28, neuropeptide Y coexpressor (historical), serostim (note: different compound — somatropin; not somatostatin)
Endogenous cyclic tetradecapeptide; somatostatin receptor ligand (SSTR1–SSTR5 agonist); inhibitory neuropeptide/hormone; parent compound of the somatostatin ana
What it is
Somatostatin is used by doctors to control abnormal hormone secretion in conditions like acromegaly and neuroendocrine tumors, to stop bleeding from esophageal varices, and to reduce pancreatic secretions after surgery or during pancreatitis. It underlies a whole family of long-acting drugs — octreotide, lanreotide, and pasireotide — that are widely prescribed worldwide.
The scientific side
somatostatin is a naturally occurring cyclic tetradecapeptide (SS-14) and its N-terminally extended 28-amino-acid form (SS-28) that acts as a broadly inhibitory hormone and neuropeptide throughout the body. Somatostatin exerts its biological actions through a family of five G-protein-coupled receptors designated SSTR1 through SSTR5, which are widely distributed in the pituitary, gastrointestinal tract, pancreas, brain, and peripheral tissues. Receptor binding activates inhibitory Gi/Go proteins, decreasing cyclic AMP production, inhibiting voltage-gated calcium channels, activating inward-rectifying potassium channels, and suppressing downstream signaling cascades including MAP kinase and PI3K pathways. The net physiological effect is predominantly inhibitory across multiple organ systems. In the pituitary, somatostatin suppresses growth hormone (GH) release from somatotroph cells and TSH secretion from thyrotrophs; this GH-suppressive action is the therapeutic basis for treating acromegaly with somatostatin receptor ligands (SRLs) such as octreotide and pasireotide. In the gastrointestinal tract and pancreas, somatostatin inhibits acid-peptic secretion, pancreatic exocrine secretion (enzymes and bicarbonate), and biliary secretion; suppresses gut motility; and reduces splanchnic blood flow by inhibiting vasodilatory gut peptides such as glucagon, VIP, secretin, and motilin. Reduced splanchnic blood flow is the mechanistic basis for somatostatin's use in acute upper gastrointestinal variceal bleeding. In the pancreatic islets, delta cells release somatostatin locally to inhibit both insulin (from beta cells) and glucagon (from alpha cells) secretion via paracrine SSTR2 and SSTR5 signaling; pharmacological activation of SSTR2/SSTR5 with somatostatin analogs suppresses pathological insulin hypersecretion, providing the rationale for octreotide and pasireotide therapy in congenital hyperinsulinism. In neuroendocrine tumors, SSTR2 overexpression is exploited both therapeutically — by delivering cytotoxic radionuclides via radiolabeled somatostatin analogs (PRRT) — and diagnostically via somatostatin receptor scintigraphy and DOTATATE PET imaging. In the brain, somatostatin functions as a neuropeptide regulating cognition and synaptic plasticity; brain SST levels are markedly reduced in Alzheimer's disease, and emerging evidence links this deficit to mitochondrial dysfunction and impaired amyloid-beta clearance. The short circulating half-life of native somatostatin (1–3 minutes) requires continuous intravenous infusion in acute settings; this pharmacokinetic limitation drove the development of longer-acting synthetic analogs.
Class: Endogenous cyclic tetradecapeptide; somatostatin receptor ligand (SSTR1–SSTR5 agonist); inhibitory neuropeptide/hormone; parent compound of the somatostatin analog (SSA) drug class
Administration & storage
- Administration
- Native somatostatin: continuous intravenous infusion only — short half-life (1–3 min) precludes other routes in acute settingsOctreotide short-acting: subcutaneous injection 2–4 times daily or IV bolus/infusionOctreotide-LAR: deep intramuscular injection (gluteal) every 28 days by healthcare professional onlyLanreotide Autogel/Depot: deep subcutaneous injection into upper outer quadrant of buttock by healthcare professional every 4 weeks (or every 6–8 weeks at higher doses in controlled disease)Pasireotide SC: subcutaneous injection twice daily (Signifor) or once monthly deep IM (Signifor LAR)Pasireotide SC off-label in neonatal CHI: individualized dosing by neonatal endocrinology team (PMID: 42723843)
- Storage
- Native somatostatin-14 lyophilized powder: store at 2–8°C (refrigerated) before reconstitution. Reconstituted IV solutions should be used promptly and not stored. Long-acting somatostatin analog depot products (octreotide-LAR, lanreotide Autogel, pasireotide-LAR): store at 2–8°C refrigerated; some formulations may have limited room-temperature excursion periods per manufacturer specifications. Do not freeze. Protect from light.
- Cautions
- Hyperglycemia and diabetes: pasireotide carries a significant risk of hyperglycemia and diabetes mellitus via SSTR5-mediated suppression of insulin secretion; blood glucose monitoring mandatory at initiation and throughout therapy. Octreotide and lanreotide cause milder, less frequent glycemic effects.,Cholelithiasis and biliary complications: all somatostatin analogs inhibit gallbladder contractility and bile acid secretion, leading to gallstone formation with long-term use. Cholelithiasis was among the most common adverse effects in long-term octreotide-LAR use for congenital hyperinsulinism. Baseline and periodic biliary ultrasound monitoring is recommended.,Bradycardia and cardiac rhythm effects: somatostatin and analogs can cause dose-dependent bradycardia, sinus pauses, and conduction abnormalities. Caution warranted in patients with pre-existing cardiac conduction disorders or bradycardia.,Rebound hormone secretion and tachyphylaxis: abrupt discontinuation of somatostatin analog therapy in acromegaly or NETs can cause rebound GH/IGF-1 surge or symptom flare. Gradual dose tapering or planned transition is recommended.,GI motility effects: somatostatin reduces gut motility; nausea, vomiting, abdominal cramping, diarrhea or constipation are common especially at treatment initiation. Usually self-limiting within a few weeks. Fat malabsorption (steatorrhea) can occur with prolonged use due to pancreatic exocrine inhibition.,Hypothyroidism: long-term SRL therapy can suppress TSH and thyroid hormone levels; thyroid function should be monitored in patients on prolonged somatostatin analog therapy.,Growth suppression in children: long-term octreotide-LAR therapy in congenital hyperinsulinism was associated with generally preserved growth velocity, but careful monitoring of height and weight trajectories is warranted; case-level growth deceleration has been reported.
Legal & regulatory status
Somatostatin (as the native peptide) is not FDA-approved as a standalone drug product in the United States. However, it is the pharmacological progenitor of three FDA-approved synthetic long-acting analogs: octreotide…
Somatostatin itself is not explicitly listed on the WADA Prohibited List as a prohibited substance. However, its analogs (octreotide, lanreotide, pasireotide) are used clinically for legitimate medical indications.…
The synthetic somatostatin analogs octreotide (Sandostatin) and lanreotide (Somatuline) are approved prescription drugs in Canada, indicated for acromegaly, gastroenteropancreatic neuroendocrine tumors, and related…
What it's studied for
- Acromegaly — suppression of excess growth hormone and IGF-1 secretion Phase III RCT
- Acute upper gastrointestinal hemorrhage — variceal and non-variceal bleeding control Human RCT
- Acute pancreatitis and peri-operative pancreatic protection Mixed
- Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) — symptom control and antiproliferative therapy Phase III RCT
- Congenital hyperinsulinism (CHI) — suppression of pathological insulin hypersecretion in neonates and children Human observational
- Alzheimer's disease — neuroprotective and amyloid-modulating role (investigational/mechanistic) Mechanistic only
- Peptide receptor radionuclide therapy (PRRT) platform — diagnostic and therapeutic target in NETs Translational / Early Clinical
Safety signals
- Hyperglycemia and new-onset diabetes mellitus (pasireotide)
- Cholelithiasis and biliary sludge with long-term use
- Bradycardia and cardiac conduction abnormalities
- Hepatotoxicity — transient liver enzyme elevations (AST, ALT)
- Gastrointestinal adverse effects — nausea, abdominal cramping, steatorrhea, altered bowel habits
- Injection site reactions with long-acting depot formulations
- Hypothyroidism with prolonged somatostatin analog therapy
- Rebound symptom flare or tumor re-growth after discontinuation
All studies (10)
Frequently asked
What is somatostatin and how is it different from octreotide or lanreotide?
Somatostatin is a naturally occurring inhibitory peptide your body produces, primarily in the hypothalamus, gut, and pancreas. It has a very short half-life of about 1–3 minutes, so it can only be given as a continuous intravenous drip in hospital settings. Octreotide and lanreotide are synthetic analogs — longer-lasting drugs designed to mimic somatostatin's actions with half-lives of hours (octreotide SC) to weeks (depot formulations). They are the FDA-approved forms used in outpatient treatment of acromegaly, neuroendocrine tumors, and related conditions.
Is somatostatin used to treat acromegaly?
Yes — but typically via its long-acting synthetic analogs, not the native peptide. Somatostatin receptor ligands (SRLs) such as octreotide-LAR and lanreotide are first-line or second-line medical therapy for acromegaly when surgery has not achieved biochemical control. These drugs suppress growth hormone and IGF-1 levels, reduce tumor size in many patients, and control symptoms. Pasireotide-LAR is used for cases resistant to first-generation SRLs. Predicting who will respond well to SRL therapy is an active research area — MRI radiomics tools are being developed for this purpose.
How does somatostatin help in gastrointestinal bleeding?
Somatostatin reduces blood flow to the gut (splanchnic circulation) and lowers portal venous pressure, which helps slow or stop bleeding from esophageal varices or other GI sources. In practice, octreotide (a synthetic analog) is most commonly used IV in hospital emergency settings for acute variceal hemorrhage, in combination with endoscopic banding or sclerotherapy. Evidence from a randomized trial suggests octreotide can be safely stopped after successful endoscopic variceal ligation without increasing rebleeding risk.
Can somatostatin be used for neuroendocrine tumors (NETs)?
Yes. Somatostatin analogs are a cornerstone of NET management. They control hormonal symptoms (diarrhea, flushing in carcinoid syndrome) and have antiproliferative effects in well-differentiated GEP-NETs. Most NETs overexpress somatostatin receptors, which is exploited both for imaging (DOTATATE PET) and for targeted radiation therapy (PRRT with 177Lu-DOTATATE). A case report described successful management of a pregnant patient with metastatic midgut NET using lanreotide after PRRT.
Is somatostatin used in children?
Yes, primarily for congenital hyperinsulinism (CHI) — a rare condition causing dangerous low blood sugar in newborns and infants due to uncontrolled insulin secretion. When first-line drug diazoxide fails, somatostatin analogs (octreotide, lanreotide, or pasireotide) are used to suppress insulin release. A retrospective study of 23 CHI children on octreotide-LAR showed most achieved normal blood glucose levels over a median follow-up of nearly 6 years, with generally preserved growth. Use is off-label and requires specialist neonatal/pediatric endocrinology management.
What are the main side effects of somatostatin analog therapy?
The most common side effects of somatostatin analogs include GI symptoms (nausea, cramping, diarrhea, or constipation — usually worst at treatment start and self-limiting), gallstone formation with long-term use (due to reduced gallbladder motility), and injection site reactions with depot formulations. Pasireotide specifically carries a significant risk of hyperglycemia and diabetes due to its broader receptor binding profile and should not be used without blood sugar monitoring. Less commonly, bradycardia, liver enzyme elevations, and hypothyroidism may occur. Regular monitoring of blood glucose, liver function, thyroid function, and biliary imaging is standard practice.
What is the role of somatostatin in Alzheimer's disease research?
Somatostatin levels are significantly reduced in the brains of people with Alzheimer's disease. Research suggests this deficit may worsen Alzheimer's pathology by impairing mitochondrial function, promoting oxidative stress in neurons, and possibly reducing clearance of amyloid-beta plaques through lower neprilysin activity. A recent review proposed a testable framework linking SST deficiency to mitochondrial dysfunction in Alzheimer's. This is an active area of research — no clinical treatments targeting somatostatin signaling for Alzheimer's are currently approved, but it represents a novel investigational avenue.