Effect of human growth hormone on amobarbital metabolism in children.

Drug metabolism changes during the course of growth and development. Hormones mediate somatic growth and may mediate other developmental changes. To determine the effect of human growth hormone (hGH) on human drug metabolism, 6 hGH-deficient children were given single oral doses of amobarbital before and 6 wk after beginning hGH replacement therapy. Amobarbital was selected as a marker of hepatic microsomal oxidation. Half-lives rose from 13.89 +/- 2.78 hr to 22.75 +/- 3.97 hr, volume of distribution was unchanged, and clearance fell from 62.2 +/- 15.2 ml/kg/hr to 31.2 +/- 11.4 ml/kg/hr. Results indicate that hGH slows the metabolism of amobarbital, probably through an effect on the hepatic microsomal drug-oxidizing system.