Effect of lanreotide, a somatostatin analogue, on urea synthesis in normal man

The aim was to investigate the effect of lanreotide (Angiopeptin) on urea synthesis. Lanreotide is a somatostatin analogue used in therapy trials of certain cancers. Cancer patients are often protein catabolic, thus the effect of lanreotide on whole body protein metabolism is of importance. We investigated the effect of lanreotide by measuring urea nitrogen synthesis rate (UNSR) and blood alpha-amino nitrogen levels before, during and after a 30 min iv infusion of 25 g of an electrolyte-free amino acid solution. 6 healthy male subjects were studied following, i) placebo (saline), ii) lanreotide 5 mug/kg, and iii) lanreotide 80 mug/kg. Lanreotide decreased urea nitrogen synthesis rate (mmol/h) during amino acid infusion significantly compared to saline, independent of dose of lanreotide (max +/- SE of urea nitrogen synthesis rate measurements in each study: 117 +/- 8 mmol/h (saline), 85 +/- 10 mmol/h (high dose) and 85 +/- 12 mmol/h (low dose)). This occurred in spite of significantly higher plasma alpha-amino nitrogen following lanreotide (peak +/- SE of alpha-amino nitrogen level in each study: 3.7 +/- 0.1 mmol/l placebo versus 4.8 +/- 0.2 mmol/l low dose and 4.7 +/- 0.4 mmol/l high dose (p < 0.01). We conclude that a single dose of lanreotide decreases whole body urea nitrogen synthesis rate thereby conserving body protein. The results indicate that long term lanreotide therapy may not lead to further protein catabolism in cancer patients.