title: Interactions between human cytochrome P450 enzymes and steroids: physiological and pharmacological implications.
abstract: BACKGROUND
  Steroids are groups of biologically active molecules with a wide variety of physiological and pharmacological functions. Human cytochrome P450 (CYP) enzymes present in probably every tissue are found responsible for biosynthesis and catabolism of steroids, which could result in either active or inactive metabolites. In addition, exposure to endogenous and exogenous steroids that causes modulation of CYP activities may substantially affect the pharmacokinetic behavior of a given drug.
  
  
  OBJECTIVE
  This article summarizes our current understanding of the ability of steroids to act as substrates, inhibitors or heteroactivators for human CYP enzymes, with a specific focus on their functional consequences.
  
  
  METHODS
  In the current review, we compare the mechanisms and regulation of CYP-mediated biotransformation of steroids, and in particular examine the diverse tissue distributions and biological roles of individual CYPs.
  
  
  CONCLUSIONS
  Metabolic instability of steroids in the presence of CYPs not only affects the magnitude and duration of their actions but may also alter the profiles of their physiological, pathological, pharmacological and toxicological effects in relevant organs.
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Ling Yang, Laboratory of Pharmaceutical Resource Discovery, Dalian, China. yling@dicp.ac.cn
authors.forename: Yan-Yan
authors.initials: YY
authors.lastname: Zhang
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
mesh_terms: D001711:Biotransformation; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology*; D004347:Drug Interactions; D006801:Humans; D013256:Steroids / Q000378:metabolism / Q000493:pharmacokinetics* / Q000494:pharmacology*; D013379:Substrate Specificity
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D013256:Steroids; D003577:Cytochrome P-450 Enzyme System