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Somatostatin and Its Analogues

Somatostatinum, Octreotidum, Lanreotidum

For medical students2 min readUpdated 2026-10-10

Somatostatin is a peptide hormone normally synthesized in the hypothalamus and peripheral tissues, acting as a potent inhibitor of endocrine and exocrine secretion. In clinical pharmacology, its synthetic analogues are used to selectively reduce visceral blood flow and effectively suppress growth hormone production without causing sharp fluctuations in systemic arterial blood pressure.

Half-lifeFrom 2–6 minutes for native somatostatin up to 7.7 days for lanreotide

HemodynamicsDecreases splanchnic arterial blood flow without altering systemic blood pressure

Routes of administrationParenteral only: intravenous, subcutaneous, or intramuscular

Main targetSuppression of growth hormone (GH) production by the anterior pituitary gland

Endogenous Hormone and Baseline Agent

Natural somatostatin is produced in the hypothalamus, where its primary role is to inhibit the secretion of growth hormone (GH) by the pituitary gland. Additionally, it is synthesized by D-cells in the gastric mucosa and pancreas, acting as a local (paracrine) inhibitor of digestive juice secretion.

In medicine, a synthetic cyclic tetradecapeptide analogue is used: Somatostatinum.

Pharmacodynamics: The drug acts selectively on hemodynamics. It significantly reduces the velocity of splanchnic blood flow and decreases the blood volume of internal organs. A crucial clinical feature is the absence of significant spikes in systemic blood pressure (BP).
Pharmacokinetics: Characterized by an extremely short half-life ($t_{1/2}$ of only 2–6 minutes). This is due to rapid degradation by plasma enzymes (aminopeptidases and endopeptidases). It is administered exclusively via continuous intravenous infusion.
Indications: Management of bleeding from esophageal varices, prevention of complications during pancreatic surgeries, and conservative treatment of fistulas (intestinal, biliary, and pancreatic).
Side effects: Bradycardia, dizziness, flushing, and dyspeptic symptoms (nausea and vomiting).

Octreotide – A Long-Acting Octapeptide

Octreotidum is a synthetic octapeptide analogue. Modifications to its molecular structure achieved a substantially prolonged duration of action: the drug acts for about 12 hours, and its half-life is approximately 100 minutes. It is administered parenterally (subcutaneously or intravenously).

Its extended duration of action significantly broadens its range of clinical indications:

Acromegaly: Octreotide suppresses GH hypersecretion. It is prescribed when surgical treatment is not feasible or when dopamine receptor agonists are ineffective.
Secretory tumors and GI disorders: Used in gastrinoma, glucagonoma, carcinoid syndrome, and severe peptic ulcer disease to potently suppress the secretory activity of glandular tissue.
Esophageal variceal bleeding: Particularly relevant for patients with liver cirrhosis (both for acute management and prevention of rebleeding).

Adverse reactions of octreotide include gastrointestinal disturbances (diarrhea, nausea, vomiting), impaired liver function, and blood glucose fluctuations. Long-term use increases the risk of developing cholelithiasis (gallstone formation). The drug is contraindicated in hypersensitivity, pregnancy, and lactation.

Lanreotide – An Ultra-Long-Acting Agent

To treat chronic conditions requiring sustained secretory suppression, Lanreotidum was developed.

Pharmacokinetics: Features an even more pronounced prolonged duration of action compared to its predecessor octreotide. Its half-life reaches 2.7–7.7 days.
Dosing regimen: Administered intramuscularly only once every 10–14 days, significantly reducing the injection burden for the patient.

Mnemonic

To remember the evolution of these agents, use the "duration rule": Somatostatin — Seconds/minutes (IV drip), Octreotide — Over half a day (hours, subcutaneous), Lanreotide — Long periods (weeks, intramuscular).

Frequently asked questions

Which hormones, aside from growth hormone, are inhibited by endogenous somatostatin?

Endogenous somatostatin inhibits several pancreatic and pituitary hormones in addition to growth hormone. These include:

Insulin — a glucose-lowering hormone.
Glucagon — a glucose-raising hormone.
Adrenocorticotropic hormone (ACTH) — an anterior pituitary hormone.
Thyroid-stimulating hormone (TSH) — a hormone stimulating the thyroid gland.

What synthetic somatostatin analogues are used in medicine besides octreotide and lanreotide?

In addition to octreotide and lanreotide, sources reference:

Somatostatin (brand name Stilamin) — a synthetic cyclic tetradecapeptide analogue; used to stop bleeding from esophageal varices, prevent postoperative complications in pancreatic surgery, and treat pancreatic, intestinal, and biliary fistulas. Very short-acting: $t_{1/2}$ is 2–6 minutes.
68Ga-DOTATOC — a somatostatin analogue used in PET imaging of meningiomas due to their high density of somatostatin receptors.

Why is somatostatin not administered in tablet form?

The peptide structure of the drug is instantly degraded by gastrointestinal enzymes. Even in blood plasma, it is broken down by endopeptidases and aminopeptidases within 2–6 minutes, which is why it is given exclusively by continuous intravenous infusion.

How does somatostatin stop esophageal variceal bleeding?

It selectively constricts splanchnic arteries and reduces visceral organ blood volume. Meanwhile, systemic blood pressure remains stable, which is critically important for critically ill patients with liver cirrhosis.

How does octreotide fundamentally differ from somatostatin?

Octreotide is a shortened (octapeptide) analogue. Due to structural modifications, it is more resistant to enzymatic degradation: its duration of action lasts about 12 hours, allowing for subcutaneous administration and the treatment of chronic conditions (such as acromegaly).

What specific risks are associated with long-term therapy using somatostatin analogues?

Due to sustained suppression of glandular secretory activity and biliary motility, long-term use of octreotide and lanreotide significantly increases the risk of cholelithiasis (gallstones) and causes blood glucose fluctuations.

Go deeper

Mechanisms of paracrine regulation by D-cells in the gastric mucosa and pancreas.
Pathogenesis of esophageal variceal bleeding in liver cirrhosis.
Principles of conservative therapy for acromegaly: the role of dopamine receptor agonists.
Secretory gastrointestinal tumors (gastrinoma, glucagonoma, carcinoid) and their metabolic effects.
Mechanism of gallstone formation (cholelithiasis) during prolonged secretory suppression.