Octreotide is a synthetic octapeptide
somatostatin analogue which has higher potency and longer duration of action than the natural
hormone. It is effective after subcutaneous administration and no rebound hypersecretion has been observed. Pharmacological effects of
octreotide include inhibition of numerous
hormones (
growth hormone, TSH,
insulin,
glucagon and all gut
hormones), of exocrine secretion (gastric acid, pancreatic
enzyme), and of small-bowel absorption. This review deals with clinical application of
octreotide in endocrine disorder. In patients with
acromegaly octreotide treatment results in decrease of
growth hormone (GH) and
IGF-I together with tumour shrinkage and clinical improvement. Although variability in response to treatment is obvious for majority of patients the most effective dose is 100 mcg three times daily subcutaneously. Normalization of GH levels could be achieved in more than 50% of treated patients. It has also been shown that
octreotide could be effective in TSH secreting
pituitary adenoma, ACTH secreting adenoma as well as in non-secretory pituitary tumours. A marked biochemical and clinical responses together with longer survival have been reported in most of the patients with gastroenteropancreatic (GEP) tumours. Patients who benefit the most from
octreotide therapy are those with carcionid syndrome (successful control of diarrhoea,
flushing episodes and
wheezing) and
VIPomas (control of diarrhoea). In patients with
insulin-dependent diabetes mellitus (
IDDM)
octreotide suppresses GH levels, postprandial
blood glucose increases with resultant decrease in daily
insulin requirements. In women with
polycystic ovary syndrome (PCOS)
octreotide has inhibitory effect on serum LH and ovarian
androgens. This could have beneficial effect on ovulatory performance in women with PCOS.