DEPOT LONG-ACTING SOMATOSTATIN ANALOG (SANDOSTATIN-LAR) IS AN EFFECTIVE TREATMENT FOR ACROMEGALY

Octreotide (Sandostatin) is a synthetic analog of somatostatin, an end ogenous GH inhibitory peptide that has been used as an adjunct to surg ery and radiotherapy in the treatment of acromegaly. When given sc in divided daily doses, it lowers serum GH to less than 5 mu g/L in appro ximately 50% of cases. Data suggest that continuous infusions of somat ostatin analogs may be more effective in lowering GH. We have evaluate d Sandostatin-LAR, a new long-acting preparation of Sandostatin, in ei ght patients with acromegaly. After an initial pharmacokinetic study, patients received a minimum of 10 im injections of Sandostatin-LAR (20 , 30, or 40 mg) at 28- or 42-day intervals. Serum GH levels decreased from 10.7 +/- 2.8 mu g/L (mean +/- SE) at baseline to a nadir of 2.6 /- 0.4 mu g/L after the tenth injection, and to less than 5 mu g/L in every patient. Serum insulin-like growth factor-I decreased from 927 /- 108 ng/mL at baseline to 472 +/- 59 ng/mL at the end of the sixth i njection and returned to normal (<500 ng/mL) in seven of the eight pat ients. This was associated with significant improvements in headache, arthralgia, and sweating. There was no evidence of octreotide accumula tion, and the drug was well tolerated. To date, no gallstones have occ urred, and serial pituitary imaging has revealed no increase in the si ze of the initial pituitary tumor. In particular, two previously untre ated patients have shown complete regression of the initial microadeno ma and have serum GH values of less than 2.5 mu g/L. Sandostatin-LAR i s an effective and well tolerated treatment for patients with acromega ly. Undoubtedly the initial indication for Sandostatin-LAR will be in the patient who is not cured after surgery and radiotherapy, but our e xperience suggests that it may be used as a primary treatment in some acromegalics.