Dose regimens of human growth hormone: effects of continuous infusion and of a gelatin vehicle on growth in rats and rate of absorption in rabbits.
Different methods for administration of human growth hormone (hGH) have been examined with a view to efficient use of the limited amounts of hGH at present available for clinical use. We found that in hypophysectomized rats (1) hGH administered by continuous subcutaneous infusion induced a greater increase in body weight (referred to throughout as growth) than hGH administered by intermittent (daily) injection and (2) intermittent injections of hGH dissolved in 16% gelatin induced more growth than hGH dissolved in a glycine buffer. It was further found that (1) hGH dissolved in 16% gelatin compared with hGH dissolved in a glycine buffer induced lower maximal levels of immunoreactive plasma hGH and between 7 and 9 h after treatment higher plasma levels when injected subcutaneously in rabbits, (2) 125I-labelled hGH added as a tracer to hGH in gelatin was removed more slowly from subcutaneous injection sites in rabbits than 125I-labelled hGH given with hGH in glycine buffer and (3) changes in the ratio of hGH to gelatin had little effect on the time-course of plasma levels of hGH in the rabbit. Addition of the protease inhibitors aprotinin or 6-aminohexanoic acid, to injection of hGH in gelatin or glycine did not induce any consistent increase in plasma levels of hGH.
D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D002021:Buffers; D004334:Drug Administration Schedule; D005780:Gelatin; D005998:Glycine; D013006:Growth Hormone / Q000008:administration & dosage* / Q000378:metabolism; D007016:Hypophysectomy; D007263:Infusions, Parenteral; D014677:Pharmaceutical Vehicles; D011817:Rabbits; D051381:Rats
D002021:Buffers; D014677:Pharmaceutical Vehicles; D005780:Gelatin; D013006:Growth Hormone; D005998:Glycine