Pharm 101: Octreotide

Class

Somatostatin analogue

Pharmacodynamics
  • Long-acting somatostatin analogue
  • Reduces splanchnic blood flow and portal venous pressure by unknown mechanisms (hence reduces variceal pressures)
  • Inhibits endocrine and paracrine factor secretion, including insulin, glucagon, gastrin, GH and TSH
  • 45 times more potent than somatostatin at inhibiting GH, but only twice as potent in reducing insulin secretion
    • Hyperglycaemia therefore rarely occurs
Pharmacokinetics
  • IV, IM, SC administration
  • Half-life 80 minutes
  • Hepatic metabolism (30-40%)
  • 20% excreted unchanged by kidney
Clinical uses
  • Acute variceal bleeding:
    • IV 50mcg bolus then 50mcg/hour infusion
    • Infusion is required because of short half-life
  • Sulphonylurea overdose
  • Reduction of symptoms of hormone secreting tumours e.g. pituitary and carcinoid tumours (long-acting injections)
Adverse effects
  • GI upset
  • Biliary: gallstones in 25% after 6 months (annual incidence of symptomatic gallstones 1%)
  • CVS: sinus bradycardia 25%, conduction disturbances 10%
  • Pain at site of injection
  • B12 deficiency with long-term use
Further reading
References
Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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