[Does the growth hormone pharmacokinetic profile help to predict the treatment response?]

Pharmacokinetics of subcutaneously administered recombinant growth hormone (rGH) were studied in nine GH deficient children at the time of the first rGH injection at the beginning of treatment. Serum GH levels were determined by four different methods: immunofunctional assay, immunofluorometric assay and two bioassays on Nb2 cells. The results showed similar profiles whatever the type of assay with a concentration peak reached 2 to 6 hours after subcutaneous injection; however, large individual variations in peak amplitude were observed. They were related to individual variations in the growth velocity during the first year of rGH treatment. These variations are possibly related to individual differences in rGH degradation at the site of injection. Study of rGH absorption profiles appears useful in the evaluation of rGH treatment in GH deficient patients.