Pharmacodynamic Modeling of the Effects of Lanreotide Autogel on Growth Hormone and Insulin-Like Growth Factor 1

Acromegaly arises from excessive levels of growth hormone (OH), many of whose effects are mediated by stimulation of secretion of insulin-like growth factor 1 (IGF-1). Synthetic somatostatin analogues inhibit CH secretion. The objective of the study was to develop a population pharmacodynamic model describing the relationship between serum concentrations of lanreotide (C-p) and its OH and IGF-1 effects in patients with acromegaly receiving lanreotide Autogel (LA) at doses of 60, 90, or 120 mg by deep subcutaneous route every 28 days. Data were analyzed from 104 patients. The GH and IGF-1 profiles were fit simultaneously using the population approach with NONMEM. The GH vs C-p and the IGF-1 vs GH relationships were described using inhibitory I-max and E-max models, respectively. Results indicated that lanreotide cannot abolish 011 completely. C-p levels of 3.4 ng/mL are required to achieve percentages of hormonal control (OH and IGF-1) of 21% and 36% in not treated and previously treated patients. If the focus is only CH, a C-p of 3.4 ng/mL corresponds to 33% and 56% controlling rates. Simulations showed that there is a possible clinical benefit if the highest dose of 120 mg LA is administered to patients who are not well controlled by lower doses of LA.