Long-term therapy with long-acting octreotide (Sandostatin-LAR) for the management of acromegaly

To evaluate the efficacy and safety of a long-acting preparation of the somatostatin analogue octreotide, Sandostatin-LAR (SMS-LAR) for the treatment of acromegaly.

Thirteen patients with acromegaly received intramuscular injections of SMS-LAR 20-40 mg at 4-6 week intervals for a period of up to 3 years.

Serial measurement of serum GH and IGF concentrations were obtained. Symptoms related to acromegaly were scored by patients at baseline and following each injection. Serial gallbladder ultrasound and pituitary imaging was performed throughout the study.

One patient was withdrawn from the study after 6 months because of continued gastrointestinal side effects; 4 patients were treated with monthly injections for 12 months and 8 patients with injections at either 1 month or 6-week intervals for 36 months; hence data is presented for n = 12 for up to 12 months; and thereafter n = 8. SMS-LAR significantly reduced serum GH and IGF-1 values: for the whole group GH concentrations fell from 24.8 +/- 4.2 mU/l (mean +/- SE) at baseline to 5.2 +/- 0.8 mU/l at 12 months (P < 0.01, n = 12). In the 8 patients treated for 3 years GH fell from 27.8 +/- 6.1 mU/l at baseline to 4.2 +/- 0.8 mU/l at the end of 3 years (P < 0.01, n = 8). GH fell to < 10 mU/l in all subjects and was < 5 mU/l in 50% after both 1 and 3 years. IGF-1 concentrations fell from 95 +/- 13 nmol/l at baseline to 63 +/- 13 nmol/l after 1 year (P < 0.01, n = 12; reference range < 65 nmol/l). In the 8 patients treated for 3 years IGF-1 concentrations fell from 119 +/- 14 nmol/l at baseline to 60 +/- 13 nmol/l after 3 years (P < 0.001, n = 8). IGF-1 was < 65 nmol/l in 60% of patients after 1 year and 75% after 3 years. Treatment resulted in trends towards improvement in symptoms of acromegaly and statistically significant improvement in sweating. There was no evidence of tachyphylaxis or evidence to suggest development of glucose intolerance. Only 2 patients (15%) developed gallbladder sludge which was asymptomatic; no patient developed gallstones.

We conclude that SMS-LAR is a safe, effective and well tolerated treatment, making it an important therapeutic option in the management of acromegaly.