Information about Octreotide
Octreotide is a synthetic somatostatin analogue that resembles the native polypeptide in its activity in suppressing levels and activity of growth hormone, insulin, glucagon and many other gastrointestinal peptides. Because its half-life is longer than somatostatin, octreotide can be used clinically to treat neuroendocrine tumors that secrete excessive amounts of growth hormone (acromegaly) or other active hormones or neuropeptides.
Liver safety of Octreotide
Octreotide has many side effects including suppression of gall bladder contractility and bile production, and maintenance therapy can cause cholelithiasis, pancreatitis as well as clinically apparent liver injury.
Mechanism of action of Octreotide
Octreotide (ok tree' oh tide) is a synthetic cyclic octapeptide and analogue of somatostatin that is used for its ability to suppress levels and activities of other hormones (growth hormone, insulin, gastrin, secretin, glucagon) or active neuropeptides (serotonin, vasoactive intestinal polypeptide [VIP]). Natural somatostatin is produced in the hypothalamus and acts to suppress growth hormone release from the pituitary. Somatostatin is also found in other neurons throughout the body and particularly in intestinal and pancreatic neurons, where it is active in suppressing release of other hormones and neuropeptides such as insulin, glucagon, gastrin, secretin, motilin, VIP, serotonin and cholecystokinin. Octreotide has a longer half-life (1 to 2 hours) than somatostatin (~3 minutes) and yields effective suppression of hormone production when given three times daily. More recently, longer acting formulations of octreotide have been developed that can be administered weekly or monthly. Octreotide appears to interact largely with the somatostatin subtype 2 and possibly subtype 5 receptors, with little effect on subtypes 1, 3 and 4, explaining its focused effects. Octreotide therapy has been shown to improve symptoms and complications of several neuroendocrine tumors including abnormal growth in acromegaly due to growth hormone secreting pituitary tumors, diarrhea due to VIP secreting intestinal tumors and flushing due to carcinoid tumors.
FDA approval information for Octreotide
Octreotide was approved for use in the United States in 1988 and current listed indications include acromegaly, watery diarrhea from VIP producing tumors and diarrhea and flushing due to metastatic carcinoid tumors. Octreotide has been used off-label for portal hypertension to control variceal hemorrhage as well as for dumping syndrome and other gastrointestinal motility disorders.
Dosage and administration for Octreotide
Octreotide is available generically and under the brand name Sandostatin in several forms for intravenous or subcutaneous administration. A long acting form is available that can be given monthly (Sandostatin LAR Depot). The typical dose in adults is 100 mcg given as injections three times daily in 2 weeks courses, and then for long term maintenace as injections 2 to 4 times daily or less frequently with long acting formulations. side effects are common.
Side effects of Octreotide
Adverse events from single injections include influenza-like symptoms of fatigue, headache, nausea and vomiting and local infusion reactions. With continued therapy, adverse events can include diarrhea, abdominal pain, back pain, headache, dizziness, hypothyroidism, hypo- and hyperglycemia, arrhythmias and gall bladder disease.