A comparison of octreotide delivered by continuous subcutaneous infusion with intermittent injection in the treatment of acromegaly

Abstract

This study was undertaken to evaluate GH, IGF1 and drug levels during incremental continuous subcutaneous infusion of octreotide and compare these parameters following long-term treatment of 300 micrograms 24 h-1 by intermittent injection in a group of acromegalic patients. Ten patients were treated by continuous subcutaneous infusion in increasing dose from 200 micrograms 24 h-1 to 1600 micrograms 24 h-1; this resulted in consistent 24-h growth hormone suppression (less than 5.0 mU l-1), and normalisation of IGF1; the optimum dose was 400 micrograms 24 h-1, the maximum dose was tolerated without any untoward effects. There was no deterioration in carbohydrate tolerance despite a marked decrease in fasting and stimulated insulin levels. After 1 year of maintenance treatment, 300 micrograms 24 h-1 by intermittent injection, patients were re-evaluated; GH levels were not so consistently suppressed over the 24-h period and carbohydrate tolerance had deteriorated. A sub-group of patients with sub-optimal GH suppression on this regimen were identified and reassessed after 6 weeks treatment with an increased dose, 600 micrograms 24 h-1 by intermittent injection; both mean GH suppression and carbohydrate tolerance improved. The dose of drug and method of administration is best adjusted for each patient to achieve optimum GH suppression, thereby minimise compensatory hyperinsuliaemia and hopefully reduce morbidity and mortality. Alterations in pituitary tumour size and acquisition of gallstones during treatment have been observed which substantiate the need to re-evaluate these parameters on routine follow-up of acromegalic patients on long-term octreotide.