Journal of Bioequivalence & Bioavailability

Abstract

Growth Hormone Bioavailability, Insulin-Like Growth Factor-I and IGFBinding-Protein-3 Release in Japanese and Caucasian Subjects

Rasmussen MH, Jøns K, Christiansen T and Madsen J

Context: The pharmacokinetics (PK) of the recombinant human GH (rhGH) is poorly documented for the Japanese adult population, and a study comparing the PK, insulin-like growth factor-I (IGF-I) and IGF-bindingprotein- 3 (IGFBP-3) release between Japanese and Caucasian subjects after rhGH administration has previously not been reported.
Objective: To compare the profiles of serum GH concentrations and the IGF-I and IGFBP-3 responses after administration of identical doses of rhGH to healthy Japanese and Caucasian subjects.
Design and Setting: A randomised, double-blind, placebo-controlled, parallel-group study.
Participants and Intervention: A total of 80 healthy male subjects (40 Japanese and 40 Caucasians) completed the study. A single dose of rhGH or placebo was administered subcutaneously, and blood samples were drawn up to 24 hours post-administration.
Main Outcome Measures: Standard PK parameters, including the area under the GH concentration–time curve from 0 to 24 hours (AUC[0-24h]) and maximum GH concentration from 0 to 24 hours (Cmax). The IGF-I and IGFBP-3 levels were measured at various timepoints during the sampling period.
Results: The bioavailabilities for Japanese and Caucasian subjects in terms of AUC(0–24 h) and Cmax were considered equivalent. The time to maximum GH concentration from 0–24 hours (tmax) was not statistically different for Japanese and Caucasian subjects. No differences in IGF-I or IGFBP-3 levels were observed. Conclusion: The bioavailabilities of rhGH for Japanese and Caucasian subjects are considered equivalent. Basal circulating IGF-I and IGFBP-3 levels and the release of IGF‑I and IGFBP-3 after administration of rhGH were similar between the two ethnic populations.