Objective: We analysed the effects of 6-months' treatment with octreotide s.c. and lanreotide-SR on circulating GH and IGF-I levels in acromegaly.
Design: Open retrospective study.
Patients: Thirty-eight patients with active acromegaly (plasma IGF-I levels greater than 2 standard deviations for age-matched controls and increased serum GH levels not suppressible by oral glucose load) were studied. All patients received s.c. octreotide at a dose of 150-600 microg/day for six months as first therapy and subsequently, lanreotide i.m., 30-60 mg either at 14 or 10 day intervals, for 6 months. A 3 months' washout was applied before starting lanreotide treatment.
Measurements: Mean serum GH levels (from three samples), IGF-I, and clinical examination were performed before and 30, 60, 90 and 180 days after octreotide and lanreotide treatments. Safety tests, HbA1c and, thyroid function were evaluated every three months.
Results: Circulating GH and IGF-I levels were significantly reduced (P < 0.001) after one, three and six months of both octreotide and lanreotide treatment. The absolute values were lower and the percent decrease in serum GH levels obtained after octreotide treatment was significantly greater, at all scheduled assessments, than after lanreotide (P < 0.01). Serum IGF-I levels during octreotide were significantly lower only after the first month of therapy (P < 0.01).
Conclusions: Our study shows that octreotide s.c. is able to induce an earlier reduction in IGF-I levels and a more marked reduction in GH levels than lanreotide. However, after six months of therapy the number of patients with safe GH levels and normal IGF-I age-matched levels, was similar with both drugs. Therefore we suggest that octreotide treatment be preferentially used in the short-term presurgical treatment, while lanreotide can be used in chronic therapy when better compliance is necessary.