Effectiveness and tolerability of slow release lanreotide treatment in active acromegaly: six-month report on an Italian multicenter study. Italian Multicenter Slow Release Lanreotide Study Group.

The objective of the study was to determine the tolerability and effectiveness of the slow release (SR) somatostatin analog lanreotide in active acromegaly. Fifty-seven patients, unselected in terms of their previous responsiveness to octreotide therapy, were included in a prospective, open label study carried out at 6 Italian endocrinological centers. The effects of 6 months of SR lanreotide, given at first every 14 days at a dosage of 30 mg, im, were recorded. In some patients (33%), drug dosage was adjusted by increasing the dose (to 60 mg, im) and/or shortening the time interval (every 10 days) of SR lanreotide administration. Fifty patients completed the 6-month period of therapy; 2 subjects dropped out because of adverse events, and 5 dropped out because of ineffectiveness after changes in drug administration. The first SR lanreotide injection produced more than 50% suppression of GH levels from the basal value in 93% of patients. Thirteen days later, baseline GH levels were reduced by over 50% in 25% of patients. Mean GH values were normalized in 85% of patients after 6 months, whereas insulin-like growth factor I (IGF-I) levels were normalized in 38% of patients. No correlation was found between pretreatment GH levels and GH response to SR lanreotide or between changes in GH and IGF-I during therapy. During treatment, there was a significant reduction in the percentage of patients complaining of joint pain, hyperhydrosis, and paresthesias. Changes in soft tissue swelling were documented by significant decreases in finger measurements. Diarrhea and abdominal pain were the most frequent side-effects when therapy was started; these progressively decreased. After the first month of therapy, moderate, mild, and no side-effects were reported by 3%, 40%, and 53% of patients. A nonsignificant increase occurred in asymptomatic gallstones and amylase levels. Minimal changes were noted in carbohydrate tolerance, consisting of a slight increase in glycosylated hemoglobin, a rise in glucose and a decrease in pre- and postprandial insulin levels. No effects on PRL, free cortisol, TSH, or free thyroid hormone levels were noted. No significant change in the percentage of visual field abnormalities was noted. Decreases in pituitary tumor size occurred in 3 of 17 patients reevaluated after 6 months of therapy. The 6-month period of SR lanreotide therapy was compared, on an anamnestic basis, with a 6-month or longer period of sc octreotide therapy (median, 300 micrograms/day) in 34 patients. There were no differences in effectiveness or tolerability between the 2 somatostatin analogs. These data indicate that SR lanreotide at a dose of 30 mg, im, every 14 days is an effective treatment in most unselected acromegalic patients. When administered to a group of poorly responsive patients, an increase in drug dose (60 mg im) and/or a shortening of the drug interval (10 days) seem to improve the GH/IGF-I response. Tolerability to SR lanreotide therapy is high. The use of a new sustained release formulation of somatostatin analog is clearly advantageous in improving patient compliance with medical treatment for acromegaly.