Octreotide acromegaly

Somatostatin Octreotide Acromegaly, carcinoid and secretory G1 tumors... 

Somatostatin has a very brief half-life in serum and is not useful clinically. An 8-amino acid analogue with 2 D-amino acids substituted for the naturally occurring L-amino acids is more stable, and monthly injections of a depot form of this analogue (octreotide, Sandostatin LAR) have several uses. Long-acting octreotide is used to treat acromegaly, as described earlier. It is also used to counteract unpleasant effects caused by overproduction of secreted bioactive substances produced by neuroendocrine tumors, including hyperinsulinemia from insulinomas and secretions from carcinoid tumors that cause severe diarrhea. Octreotide may also control severe diarrhea associated with AIDS that has not responded to other treatments. 

Withdraw octreotide yearly for 4 wk in acromegaly patients who have received irradiation to assess disease activity... 

A long-acting formulation of lanreotide, another octapeptide somatostatin analog, was approved by the FDA in 2007 for treatment of acromegaly. Lanreotide appears to have effects comparable to those of octreotide on reducing GH levels and normalizing IGF-1 concentrations. 

A dopamine agonist alone or in combination with pituitary surgery, radiation therapy, or octreotide administration can be used to treat acromegaly. The doses required are higher than those used to treat hyperprolactinemia. For example, patients with acromegaly require 20-30 mg/d of bromocriptine and seldom respond adequately to bromocriptine alone unless the pituitary tumor secretes prolactin as well as GH. 

Lanreotide Similar to octreotide and available as a long-acting formulation for acromegaly ... 

Because it inhibits pancreatic secretion, octreotide may be of value in patients with pancreatic fistula. The role of octreotide in the treatment of pituitary tumors (eg, acromegaly) is discussed in Chapter 37. Octreotide is sometimes used in gastrointestinal bleeding (see below). 

Sinus bradycardia (less than 50/minute) is reported in up to 25% of acromegalic patients taking octreotide, and conduction abnormalities are also commonly reported in these patients. This adverse effect is reported only rarely in other recipients of somatostatin or octreotide, probably reflecting the high rate of cardiac abnormalities due to acromegaly (9). 

In 24 patients with acromegaly, glucose homeostasis was assessed before and after 6 months of either 2-weekly lanreotide (n = 14) or monthly octreotide (n = 10) (21). Insulin resistance and triglyceride concentrations improved. Glucose homeostasis, measured by HbAic, deteriorated. This was probably due to impaired insulin secretion. There were no distinct differences between the analogues, but the numbers were small. 

Hair loss in a 36-year-old man began after he had taken octreotide for acromegaly for 1 month (48). Therapy was changed to lanreotide after 6 months and hair loss reversed. This may have been coincidental. 

Davies PH, Stewart SE, Lancranjan L, Sheppard MC, Stewart PM. Long-term therapy with long-acting octreotide (Sandostatin-LAR) for the management of acromegaly. Clin Endocrinol (Oxf) 1998 48(3) 311-6. 

Thomas LA, Veysey MJ, Murphy GM, Russell-Jones D, French GL, Wass JAH, Dowling RH. Octreotide induced prolongation of colonic transit increases fecal anaerobic bacteria, bile acid metabolizing enzymes, and serum deoxy-cholic acid in patients with acromegaly. Gut 2005 54 630-5. 

Avila NA, Shawker TH, Roach P, Bradford MH, Skarulis MC, Eastman R. Sonography of gallbladder abnormalities in acromegaly patients following octreotide and ursodiol therapy incidence and time course. J Clin Ultrasound 1998 26(6) 289-94. 

Turner HE, Lindsell DR, Vadivale A, Thillainayagam AV, Wass JA. Differing effects on gall-bladder motility of lan-reotide SR and octreotide LAR for treatment of acromegaly. Eur J Endocrinol 1999 141(6) 590 1. 

Atmaca A, Erbas, T. Lipoatrophy induced by subcutaneous administration of octreotide in the treatment of acromegaly. Exp Clin Endocrinol Diabetes 2005 113 340-3. 

Lami M-C, Hadjadj S, Guillet G. Hair loss in three patients with acromegaly treated with octreotide. Br J Dermatol 2003 149 655-6. 

Barkan AL, Burman P, Clemmons DR, Drake WM, Gagel RF, Harris PE, Trainer PJ, van der Lely AJ, Vance ML. Glucose homeostasis and safety in patients with acromegaly converted from long-acting octreotide to pegvisomant. J Clin Endocrinol Metab 2005 90 5684-91. 

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