RESUMEN
OBJECTIVE: Slow-release (SR) lanreotide is a long-acting somatostatin analog that has been developed in order to overcome the inconvenience of multiple daily subcutaneous injections of octreotide, required for metabolic control in acromegaly. Lanreotide SR has been found to be well tolerated and effective in reducing GH and IGF-I levels but clinical data are still limited compared with those with subcutaneous octreotide treatment. DESIGN: Sixty-six unselected patients with active acromegaly were therefore evaluated in a multi-center, prospective, open label study. Lanreotide SR was given at a dose of 30mg intramuscular every 7-14 days. METHODS: At baseline and after 2, 4, 8, 12, 24, 36 and 48 weeks patients underwent a clinical examination with assessment of acromegaly related symptoms, and blood was sampled for serum GH, IGF-I, prolactin, glycosylated hemoglobin, fasting glucose, hematology, kidney function and liver function tests. Biliary ultrasonography and pituitary magnetic resonance imaging were performed at baseline and after one year. RESULTS: Treatment resulted in a significant improvement in the symptom score from 2.69+/-0.27 to 1.06+/-0.17 (P<0.0001). Serum IGF-I levels fell from 699+/-38microg/l at baseline to 399+/-26microg/l (P<0.0001, n=60) after one month, after which levels remained stable: 480+/-37microg/l after 6 months (n=54) and 363+/-32microg/l after one year (n=46). GH levels dropped from 13.8+/-3.2microg/l to 4.3+/-0.7microg/l after one month (P<0.0001, n=60) and remained stable thereafter: 3.9+/-0.4microg/l (n=54) after 6 months and 3.5+/-1.1microg/l after one year (n=46). Twenty-nine out of 66 patients (44%) attained a normal age-corrected IGF-I level and 30 patients (45%) attained a GH level below 2.5microg/l. Pituitary adenoma shrinkage of at least 25% was found in 5 of 14 patients (36%) after one year. Side effects were mainly transient gastrointestinal symptoms and pain at the injection site, resulting in drug discontinuation in only 6 patients (9%). Two patients developed new gall stones. No difference was found between subcutaneous octreotide and lanreotide SR in efficacy and almost all patients preferred the easier dose administration of lanreotide SR. CONCLUSIONS: Long-term treatment of acromegaly with SR-lanreotide is effective in controlling GH and IGF-I levels and symptoms and is well tolerated in the majority of patients. Compared with subcutaneous octreotide, lanreotide SR considerably improves patient's acceptance of therapy while having the same overall efficacy.