Octreotide Acetate — Drug Monograph

Brand names: Sandostatin, Sandostatin LAR

Drug class: Somatostatin Analog

Mechanism of Action

Synthetic octapeptide analogue of native somatostatin with markedly prolonged duration of action. Binds preferentially to somatostatin receptor subtypes SSTR2 and SSTR5, which are overexpressed on most well-differentiated neuroendocrine tumors. Receptor activation inhibits: (1) peptide hormone secretion (insulin, glucagon, GH, VIP, gastrin, motilin, secretin), directly ameliorating hormone-excess syndromes; (2) intestinal secretion and motility, reducing diarrhea and flushing in carcinoid syndrome; and (3) tumor cell proliferation — antiproliferative effects demonstrated in the PROMID trial…

FDA Indications

• Carcinoid syndrome — control of flushing episodes and profuse watery diarrhea
• Vasoactive intestinal peptide-secreting tumors (VIPomas) — treatment of profuse watery diarrhea
• Acromegaly — reduction of GH and IGF-1 in patients inadequately controlled by surgery or who are not candidates for surgery

Common Side Effects

• Nausea, diarrhea, abdominal pain, flatulence (especially during initiation)
• Cholelithiasis (gallstones): ~50% of patients with long-term use — from inhibited gallbladder contraction
• Glucose metabolism abnormalities: hypoglycemia (inhibits insulin counter-regulation) or hyperglycemia (inhibits insulin secretion)
• Hypothyroidism (long-term use)
• Injection site reactions (SC formulation)
• Bradycardia and conduction abnormalities (sinus bradycardia, QT prolongation)

Clinical Pearl

The PROMID trial (midgut NETs) and CLARINET trial (lanreotide) established somatostatin analogues as antiproliferative agents for well-differentiated advanced NETs — a paradigm shift beyond their original symptom-control role. For patients on SSA therapy who require ¹⁷⁷Lu-DOTATATE (PRRT), the LAR formulation must be withheld for 4–6 weeks before each treatment cycle — this washout interval is critical to allow competitive SSTR2 binding to clear and maximize the PRRT dose to tumors.…

Related Therapies & Mechanisms

• Lanreotide (Somatuline Depot) — Somatostatin Analog · NET
• Capecitabine (Xeloda) — NET
• CAPTEM Regimen (Capecitabine + Temozolomide) (Xeloda + Temodar) — NET
• Everolimus (Afinitor) — NET