Somatostatin analog
Octreotide (Sandostatin)
Also called Sandostatin
Indications
- Acute variceal bleeding, started on suspicion and continued 2–5 days with band ligation and antibiotics (off-label)
- Carcinoid crisis and carcinoid syndrome flushing and diarrhea, including during anesthesia
- Recurrent hypoglycemia after sulfonylurea overdose (off-label)
- High-output fistula, chylothorax or secretory diarrhea (off-label)
- Hepatorenal syndrome with midodrine and albumin when terlipressin or norepinephrine cannot be used (off-label)
- GI bleeding from angiodysplasia, including in LVAD patients (off-label)
Dosing
Octreotide drip card and mL/h converterStart: 50 mcg bolus, then 50 mcg/h
Mechanism of action
Octreotide, an 8-amino-acid analog of the 14-amino-acid hormone somatostatin, binds somatostatin receptors, mainly SSTR2 and SSTR5. These Gi/o-coupled receptors inhibit adenylyl cyclase, open potassium channels and close calcium channels, so cells release less growth hormone, insulin, glucagon, TSH, gastrin, VIP and serotonin. Suppressing glucagon and other vasodilator peptides constricts splanchnic arterioles and cuts portal inflow, but each bolus lowered portal pressure for only about 5 min, an infusion did not sustain it, and repeat boluses worked less (Escorsell 2001).
Pharmacology
- GI: lowers splanchnic and portal flow; slows motility; cuts pancreatic and intestinal secretion and fistula output
- Endocrine: inhibits growth hormone, glucagon and insulin more potently than somatostatin; glucose can rise or fall
- Cardiovascular: bradycardia (under 50/min in 25% of acromegaly patients) and conduction delay (label); MAP rises briefly after a bolus
- Hepatobiliary: inhibits gallbladder contraction, so sludge and stones form with prolonged use
- Other: suppresses TSH; reduces fat absorption and vitamin B12
Pharmacokinetics
| Onset | IV: immediate; SC: peak level in about 25 min |
|---|---|
| Duration | Hormone suppression up to 12 h after an SC dose (label); the portal effect of a bolus lasts minutes |
| Half-life | 1.7–1.9 h, against 1–3 min for native somatostatin (label) |
| Distribution | Vd 13.6 L (about 0.2 L/kg), largely extracellular |
| Protein binding | About 65%, mainly to lipoproteins |
| Clearance | 7–10 L/h; about 4.5 L/h in dialysis-dependent renal failure (label) |
| Elimination | About 32% unchanged in urine; the rest mostly hepatic |
| Organ failure | Cirrhosis: half-life 3.7 h; older adults: half-life 46% longer (label) |
| Routes | IV bolus and infusion or SC (bioequivalent); monthly IM depot for chronic disease |
Chemistry
- Cyclic octapeptide D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-ol with a disulfide bridge (MW 1,019)
- Keeps somatostatin's Phe-Trp-Lys-Thr binding turn; the D-amino acids, ring and C-terminal threoninol block peptidases, stretching the half-life from minutes to nearly 2 h
- Water-soluble acetate salt in vials of 50–1,000 mcg/mL; multiple-dose vials contain phenol; refrigerate (14 days at room temperature, protected from light)
- Stable 24 h in NS or D5W; incompatible with TPN (label)
Adverse effects and cautions
In the one-pagers
- GI Bleeding, Liver Failure and PancreatitisUpper GI bleeding: Vasoactive drug: Octreotide as soon as suspected, 2–5 days
- Acute Abdomen and GI Surgical EmergenciesWhipple, bariatric and gastric surgery in depth: Dumping (Masclee 2023) follows gastric surgery, bypass and sleeve: up to 40% after bypass or sleeve. Early dumping (within 1 hour) is a fluid shift into the gut from hyperosmolar chyme: fullness, cramps, diarrhea, palpitations, sweating, faintness. Late dumping (1-3 hours) is reactive hypoglycemia. Treatment steps: smaller, more frequent meals rich
- LVAD BasicsComplications: bleeding, stroke, infection, RV failure: Hold warfarin (and aspirin in HeartMate II or HVAD patients), reverse only for life-threatening bleeding with a high INR, and scope early. For recurrent bleeding ISHLT 2023 lists a lower INR target, octreotide and thalidomide as options with thin evidence.
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Sources
- FDA label: Sandostatin (2024)
- Escorsell 2001 (octreotide desensitization)
- Baveno VII consensus (2022)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.