Continuous versus intermittent subcutaneous infusion of octreotide in the treatment of acromegaly

This review evaluates the efficacy, tolerability, and safety of continuous subcutaneous infusion (CSI) relative to intermittent subcutaneous injection (ISI) of the somatostatin analog, octreotide in the treatment of acromegaly. Data was extracted from five clinical series using CSI octreotide in acromegaly, six reports comparing CSI to ISI, and three studies comparing pulsatile subcutaneous infusion (PSI) to ISI. Effects of each drug regimen on the control of growth hormone (GH), insulin-like growth factor (IGF-1), clinical symptomatology, pituitary tumor size, and adverse effects were evaluated. Normalization of serum GH or IGF-1 levels, as well as improvement in clinical symptoms was reported in the majority of the patients studied. Cases in which pituitary adenomas decreased in size were also documented during the study period. When the effects of CSI were compared with ISI, a more pronounced control of GH and IGF-1 was observed. In addition, diurnal GH fluctuation during CSI was significantly reduced relative to ISI in two reports. Moreover, in two patients, CSI achieved similar clinical and biochemical effects at lower doses than when the drug was given by ISI. Finally, adverse effects with CSI may be less severe than with ISI. Continuous subcutaneous infusion of octreotide produced biochemical improvement in 67 of the 88 patients reviewed. When compared with ISI, CSI induced more pronounced biochemical control, often with less fluctuation in GH and IGF-1 levels. Because of a lack of data, definite conclusions regarding the differences between regimens on clinical symptomatology and tolerability could not be discerned. A large prospective, long-term randomized crossover study is recommended to make these determinations.