Pharmacokinetic profile of recombinant human insulin-like growth factor I given subcutaneously in normal subjects.

The pharmacokinetic profile of recombinant human insulin-like growth factor I (IGF-I) was studied in healthy volunteers. Following a single subcutaneous injection of 40 micrograms/kg or 80 micrograms/kg, mean serum IGF-I concentrations increased by 150 ng/ml and 245 ng/ml, respectively. During repeated daily injections of 40 micrograms/kg, a steady-state IGF-I level of 150 ng/ml above baseline was reached. Of the pharmacokinetic indices measured, only Tmax varied between single and multiple dose regimens (6.9 hours versus 3.5 hours). No hypoglycaemic symptoms were observed, and after injection of IGF-I no depression of endogenous IGF-I production was observed. Fasting insulin levels were unaltered, but postprandial insulin was lowered by IGF-I with respect to placebo.