Octreotide (Sandostatin) is a synthetic octapeptide analog of somatostatin, the mainstay of medical therapy for acromegaly and GEP-NETs.
Structure
8-amino acid cyclic peptide with disulfide bridge: D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-ol (cyclic)
Half-life extended from 2-3 minutes (native somatostatin) to ~90 minutes.
Mechanism of Action
Binds somatostatin receptors (especially SSTR2):
- Inhibits adenylyl cyclase
- Suppresses hormone secretion (GH, insulin, glucagon, gastrin)
- Anti-proliferative effects on NETs
FDA-Approved Indications
- Acromegaly: Improves symptoms in 70% of patients
- Carcinoid Tumors: Controls flushing and diarrhea
- VIPomas: Controls profuse watery diarrhea
- GEP-NETs: Anti-proliferative effects (PROMID study)
Formulations
| Formulation | Dosing |
|---|---|
| Sandostatin | 50-200 mcg SC 2-3x daily |
| Sandostatin LAR | 10-30 mg IM every 28 days |
| Mycapssa (oral) | 20mg twice daily |
Mycapssa (June 2020) is the first oral somatostatin analog approved by FDA.
Safety
GI side effects common. Gallstones in 15-30% with long-term use. Monitor gallbladder, glucose, thyroid function.