Plasma human growth hormone (hGH) profiles and biological activities of recombinant hGH were compared after im and sc injection in 8 normal volunteers. The time to reach maximal plasma GH and plasma hGH concentrations and the areas under the curve of hGH profiles did not differ significantly after im and sc injections. The biological effect of hGH in increasing nonesterified fatty acid and insulin-like growth factor-I (IGF-I) was the same after both im and sc injections.
During 6 months of daily sc administration of recombinant hGH in 20 naive patients, their height increased between 5 and 16.5cm with a mean of 11.0±3.0cm/year. In 27 patients who switched from hGH injections of 2-4 times/week to daily injections, the height increased between 5.3 and 16.5cm with a mean of 8.3±2.2 cm/year. These values were greater than those observed in a previous study in which the same amount of hGH was injected in 2-4 doses per week. Plasma IGF-I increased more with daily sc administration than with 2-4 doses per week. The rate of appearance of an antibody to hGH was low (0.5%) and there were no notable changes in blood cell count, urinalysis and/or routine chemistries during the 6 months of daily recombinant hGH treatment.
These results show that sc daily administration of hGH is safe, has a greater growth promoting effect, and can be recommended for the treatment of patients with GH deficiency.