Octreotide

Octreotide is a synthetic analogue of somatostatin, a natural inhibitory hormone. It mimics somatostatin but is longer-acting, enabling sustained suppression of multiple endocrine and exocrine secretions. It is used to treat hormone-secreting tumors and certain complications of portal hypertension.

In acromegaly, octreotide markedly reduces growth hormone and IGF-1, improving symptoms and biochemical control. It is effective in managing carcinoid syndrome and VIPoma, and can decrease secretory diarrhea from gastrinomas or other neuroendocrine tumors. The drug also reduces portal venous pressure and can help control bleeding from esophageal varices, sometimes used preoperatively to reduce splanchnic blood flow.

Octreotide binds somatostatin receptors, principally SSTR2 and SSTR5, inhibiting release of hormones such as GH, glucagon, insulin, serotonin, and vasoactive intestinal peptide. It also decreases pancreatic secretions and slows gastrointestinal motility.

Formulations include a short-acting form given by subcutaneous injection two to three times daily, and a long-acting release (LAR) depot given intramuscularly every four weeks. The short-acting form has a half-life of about 1.5 hours, while LAR provides sustained effects.

Common adverse effects are gastrointestinal symptoms (nausea, diarrhea, abdominal pain) and biliary issues such as gallstones and biliary sludge with long-term use. Glucose tolerance may be impaired, leading to hyper- or hypoglycemia. Other effects include bradycardia and injection-site reactions. Monitoring may include gallbladder ultrasound and glucose testing; dose adjustments are based on response and tolerability.