Endocrine Abstracts

Adult growth hormone replacement is currently given by daily sc injections in the vast majority of children and adults treated for growth hormone (GH) deficiency. In recent years, sustained-release preparations of GH have been developed; the preparations available so far maintained therapeutic GH concentrations for approximately 14 days, but were characterised by a dominant early release, which resulted in high supraphysiological early GH peaks, and a rapid decline thereafter.

hGH-Biosphere® (SkyePharma Inc, San Diego, USA) is a new sustained-release GH preparation of 10mg GH in 123mg of amylopectin microcapsules coated in lactic and glycolic acid co-polymers. We present pharmacokinetic, pharmacodynamic and safety data of this preparation in eight adult patients with untreated GH deficiency. The systemic and local tolerability of the drug were satisfactory, and no serious adverse events occurred. PK analysis showed a smaller early serum hGH peak followed by a broad sustained second peak of hGH (Cmax 1.20 μg/L at 7.2 days). The mean GH level never exceeded 1.1μg/L, making the GH fluctuations comparable to those seen with continuous sc infusion. Resultant IGF-I concentrations were characterised by sustained elevation at a level near Cmax of 103 μg/L at 9.7 days), equal to a standard deviation score of +0.8. IGF-I generation per administered GH was more efficient compared with other sustained-release preparations, while avoiding supraphysiological GH concentrations at any stage. Our data suggest that this preparation is suitable for longer-term trials in adults with injection frequencies of no more than once every 2 to 3 weeks.