Reduced Activities of Cytochrome P450 1A2 and Xanthine Oxidase in Children With Growth Hormone Deficiency

Growth hormone (GH) regulates the sex‐specific expression of drug‐metabolizing enzymes (DMEs),1 and it has been shown that the clearance of multi‐enzymatic substrates is altered following GH replacement.2,3 Baseline pharmacokinetic alterations have also been described, suggesting that GH deficiency itself alters DME activity.3,4,5 However, the effects on individual enzymes have not been characterized. We therefore assessed the activity levels of DMEs that are likely to be affected in children with GH deficiency (a condition that affects 1 in 3,500 children)6 and compared them with pediatric historical controls.7 Clinical Pharmacology & Therapeutics (2008); 84, 6, 674–678 doi:10.1038/clpt.2008.185