Somatostatin
Also known as: GH-RIH, Modustatin, Somatotropin Release‑Inhibiting Factor, SRIF, SRIF (Somatotropin Release-Inhibiting Factor), SST, SST-14, SST-28, Stilamin
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Summary
Somatostatin is a cyclic neuropeptide hormone that inhibits the secretion of several other hormones and reduces splanchnic blood flow. Clinically, its synthetic analogues are used to control excess growth hormone in acromegaly, to manage acute variceal bleeding, and have been investigated for high‑output stoma, enterocutaneous fistula, acute pancreatitis, and gastrointestinal angiodysplasia.
Mechanism of Action
Somatostatin binds to somatostatin receptors (SSTR1‑5) on target cells, triggering intracellular pathways that suppress the release of hormones such as growth hormone, insulin, glucagon and gastrointestinal peptides. In the liver and portal circulation it reduces splanchnic blood flow, contributing to haemostatic effects in acute bleeding. The inhibition of hormone secretion underlies its utility in acromegaly and related disorders.
What the Research Shows
Randomised trials in acromegaly show that patients maintained biochemical control when switched from injectable somatostatin receptor ligands to an oral SSTR2 agonist, indicating the effectiveness of receptor activation. A systematic review of acute variceal bleeding found somatostatin (with octreotide) provided mortality outcomes comparable to vasopressin but with fewer adverse events. Meta‑analyses of high‑output stoma and enterocutaneous fistula reported no clear benefit from somatostatin analogues. In acute pancreatitis, very low‑quality evidence suggests somatostatin combined with omeprazole may lower serious adverse events, though mortality was unchanged. For gastrointestinal angiodysplasia, pooled data suggest somatostatin analogues may reduce re‑bleeding and transfusion needs, but the magnitude of effect remains uncertain.
Reported Benefits
Evidence supports somatostatin‑based therapy for suppressing excess growth hormone in acromegaly, achieving biochemical control in most patients. In acute variceal bleeding, somatostatin offers similar survival to vasopressin while causing fewer side‑effects. Limited data indicate possible reductions in re‑bleeding and transfusion requirements in gastrointestinal angiodysplasia and a modest decrease in serious adverse events when combined with omeprazole in acute pancreatitis.
Limitations of the Evidence
Most findings are derived from low‑ to moderate‑quality studies with small sample sizes and heterogeneous definitions. No mortality benefit has been demonstrated in acute pancreatitis or high‑output stoma. The benefit in gastrointestinal angiodysplasia is suggested but not definitively quantified. Guidelines for enterocutaneous fistula acknowledge unclear efficacy, and many trials report high risk of bias.
Safety Considerations
Common adverse effects of somatostatin and its analogues include gastrointestinal symptoms (nausea, abdominal pain, diarrhoea), hyperglycaemia, and gallstone formation with prolonged use. In acute bleeding studies, somatostatin was associated with fewer adverse events than vasopressin. The oral SSTR2 agonist paltusotine reported typical SRL‑related GI effects. Caution is advised in patients with diabetes or gallbladder disease.
How It Is Administered
Somatostatin is administered intravenously, often as a continuous infusion for acute bleeding. Synthetic analogues are typically given subcutaneously or intramuscularly for chronic conditions such as acromegaly. Formulations are supplied as sterile solutions; oral formulations are not available for the native peptide.
Routes of Administration
Goals & Uses
- Inhibit excess hormone secretionEndocrine ControlModerate
- Inhibition of pancreatic secretion / fistula managementGastroenterology / SurgeryModerate
- Suppression of growth hormone secretionEndocrinologyModerate
- Control of acute variceal bleedingHemostasis / GastroenterologyHigh
- Reduction of hormone hypersecretion in carcinoid/VIPomaOncology / EndocrinologyLow
- Management of acute gastrointestinal bleedingGastroenterologyModerate
Contraindications
- Known hypersensitivity to somatostatinAllergyHigh
- PregnancyPopulationModeratePotential fetal risk or insufficient safety data
- LactationReproductiveModerate
Adverse Effects
- Injection site reactionsLocalUncommon
- Gastrointestinal discomfortGastrointestinalCommon
- FlushingVascularUncommonWarmth and redness of the skin
- Nausea and vomitingGastrointestinalCommon
- Altered glucose homeostasisMetabolicUncommon
- Hypoglycemia / HyperglycemiaMetabolic / EndocrineCommon
- Abdominal discomfort / diarrheaGastrointestinalCommon
- BradycardiaCardiovascularUncommon
Drug Interactions
- InsulinModerateMay increase risk of low blood sugar
- Oral hypoglycemics (e.g., sulfonylureas)Moderate
- Antihypertensives / Beta-blockersLow
- CyclosporineModerate
- BromocriptineLow
- Insulin / Oral hypoglycemicsModerate
Population Constraints
- Hepatic / Renal impairmentOrgan ImpairmentRelative
- Pediatric patientsAgeRelative
- Pregnant womenReproductiveRelative
- Diabetic PatientsMetabolicRelative
- Patients with cardiac conduction disordersCardiovascularRelative
Regulatory Status
- European UnionUnapprovedSame as US; used in research contexts.
- United StatesUnapprovedNot marketed as a drug; available for research use only.
- United KingdomUnapprovedNo therapeutic licensing.
Not approved as a therapeutic agent in major jurisdictions; employed mainly in research and diagnostic settings.
Evidence & Sources
- Journal ArticleModerateGadelha MR, et al.2024-01-01T00:00:00.000000Z
- Journal ArticleHighHuaringa-Marcelo J, et al.2021-01-01T00:00:00.000000Z
- Journal ArticleHighLederhuber H, et al.2023-01-01T00:00:00.000000Z
- Journal ArticleHighKumpf VJ, et al.2017-01-01T00:00:00.000000Z
- Journal ArticleHighMoggia E, et al.2017-01-01T00:00:00.000000Z
- Journal ArticleHighGoltstein LCMJ, et al.2021-01-01T00:00:00.000000Z
Frequently Asked Questions
How does somatostatin help patients with acromegaly?
Somatostatin activates receptors that suppress growth‑hormone secretion, lowering insulin‑like growth factor‑1 levels. Clinical trials show most patients maintain biochemical control when switched from injectable receptor ligands to an oral SSTR2 agonist, reflecting the peptide’s underlying mechanism.
Is somatostatin effective for stopping bleeding from oesophageal varices?
In randomized studies, somatostatin (used with octreotide) achieved mortality rates similar to vasopressin but caused fewer adverse events. It reduces splanchnic blood flow, helping to control acute variceal bleeding, though it does not appear superior in survival.
Can somatostatin reduce the need for blood transfusions in gastrointestinal angiodysplasia?
A systematic review and individual‑patient data meta‑analysis suggest somatostatin analogues may lower re‑bleeding rates and transfusion requirements, but the exact benefit size is uncertain and evidence quality is moderate.
What are the main side effects to watch for when using somatostatin?
Typical side effects include nausea, abdominal discomfort, diarrhoea, elevated blood glucose, and, with long‑term use, gallstone formation. Compared with vasopressin, somatostatin shows a more favourable safety profile in acute bleeding settings.
Is there a role for somatostatin in treating high‑output stomas or fistulas?
Current systematic reviews find no convincing evidence that somatostatin analogues reduce stoma output or improve outcomes in enterocutaneous fistula, and guidelines note the benefit remains unclear.
What is Somatostatin?
Somatostatin is a cyclic neuropeptide hormone that inhibits the secretion of several other hormones and reduces splanchnic blood flow. Clinically, its synthetic analogues are used to control excess growth hormone in acromegaly, to manage acute variceal bleeding, and have been investigated for high‑output stoma, enterocutaneous fistula, acute pancreatitis, and gastrointestinal angiodysplasia.
What is Somatostatin used for?
Somatostatin is educationally associated with: Inhibit excess hormone secretion, Inhibition of pancreatic secretion / fistula management, Suppression of growth hormone secretion, Control of acute variceal bleeding, Reduction of hormone hypersecretion in carcinoid/VIPoma, Management of acute gastrointestinal bleeding. Educational only — not medical advice.
How is Somatostatin administered?
Recorded routes of administration: Intrathecal, Intravenous, Subcutaneous.
What are the potential side effects of Somatostatin?
Reported adverse effects include: Injection site reactions, Gastrointestinal discomfort, Flushing, Nausea and vomiting, Altered glucose homeostasis, Hypoglycemia / Hyperglycemia, Abdominal discomfort / diarrhea, Bradycardia. This list is not exhaustive — consult a qualified clinician.
Who should avoid Somatostatin?
Recorded contraindications: Known hypersensitivity to somatostatin, Pregnancy, Lactation. Consult a qualified clinician before use.