[Somatostatin analog (octreotide) in clinical use: current and potential indications]

The long-acting somatostatin analogue octreotide is a synthetic cyclic peptide consisting of 8 amino acids. Depending on the organ, it acts either as a hormone or as a neurotransmitter. The effect on various physiological functions in the brain and the gastrointestinal tract is mainly inhibitory. Due to its inhibitory actions, the possibility of intravenous and subcutaneous administration and the lack of serious side-effects, octreotide offers a broad spectrum of possible indications. Today octreotide is recommended in acromegaly patients and for the treatment of hormone dependent symptoms in patients with gastroenteropancreatic tumours. New indications are enterocutaneous and pancreatic fistulas and the prevention of complications in major pancreatic surgery. In patients with dumping and short-bowel syndrome, octreotide may be helpful until dietary regimens are established. In Aids patients with severe diarrhea, octreotide can be used to stabilize patients with severe dehydration and malnutrition. The clinical effectiveness on upper GI-bleeding due to gastric ulcer and oesophageal varices is still controversial. Future studies must prove whether octreotide may be helpful in treating diabetic retino- and nephropathy because of the possibility of suppressing growth hormone and IGF-I. The antiproliferative effect of octreotide also allows its use in patients with somatostatin-receptor-positive, non-endocrine solid tumors (e.g. brain, breast and small-cell lung cancer). A promising area is the scintigraphic visualization of somatostatin-receptor-positive tumors with a radio-labelled octreotide analogue and the possible target irradiation of these tumors by beta-particle emitting isotopes attached to such analogues.