OCTREOTIDE LONG-ACTING RELEASE (LAR) - A REVIEW OF ITS PHARMACOLOGICAL PROPERTIES AND THERAPEUTIC USE IN THE MANAGEMENT OF ACROMEGALY

Octreotide is a somatostatin analogue a long-acting release (LAR) form ulation of octreotide is designed for once-monthly intramuscular admin istration. As with native somatostatin, octreotide LAR exerts potent i nhibitory effects on the secretion of growth hormone and on various pe ptides of the gastroenteropancreatic endocrine system. When patients w ith acromegaly who show a positive response to treatment with subcutan eous octreotide 300 to 600 mu g/day are switched to octreotide LAR 20 or 30mg, the resulting decrease in growth hormone levels is stable and sustained. Reductions in growth hormone levels to <5 mu g/L for about 4 weeks are seen in 86 to 100% of patients, to <2 to 2.5 mu g/L in 39 to 75% and to <1 mu g/L in 24 to 40%. Levels of insulin-like growth f actor-1 (IGF-1) decrease in parallel and are often normalised with rep eated drug treatment. There is no evidence of tachyphylaxis with long term therapy (up to 34 months). Treatment with octreotide LAR improves facial appearance and soft tissue thickening, and eliminates or reduc es the incidence of symptoms such as headache, fatigue, arthralgia and excessive perspiration. Tumour shrinkage has been noted in some, but not all, patients receiving octreotide LAR, although this has not been widely evaluated in clinical studies. Overall, octreotide LAR is well tolerated, and the mild to moderate gastrointestinal events experienc ed by up to 50% of patients are of short duration and often subside wi th continued drug administration. The incidence of gallbladder abnorma lities (sediment, sludge, microlithiasis and gallstones) increases in patients receiving long term therapy with subcutaneous octreotide, alt hough most patients remain asymptomatic. The incidence of gallbladder abnormalities in patients receiving octreotide LAR compares favorably with that during subcutaneous administration Glycaemic control is not usually altered during octreotide LAR treatment. In summary octreotide continues to be the principal pharmacological option for most patient s with acromegaly. Octreotide LAR offers the convenience of once-month ly administration compared with daily subcutaneous drug administration . In addition, the good efficacy and tolerability profile of octreotid e LAR should enhance patient compliance and acceptability of octreotid e therapy and contribute to an improvement in patient quality of life.