Editing CYP3A4 (section)

== Tissue distribution ==
[[Fetus]]es do not express ''CYP3A4'' in their liver tissue, but rather ''[[CYP3A7]]'' ({{EC number|1.14.14.1}}), which acts on a similar range of substrates. CYP3A4 increases to approximately 40% of adult levels in the fourth month of life and 72% at 12 months.<ref name="pmid16928154">{{cite journal | vauthors = Johnson TN, Rostami-Hodjegan A, Tucker GT | s2cid = 25596506 | title = Prediction of the clearance of eleven drugs and associated variability in neonates, infants and children | journal = Clinical Pharmacokinetics | volume = 45 | issue = 9 | pages = 931–56 | year = 2006 | pmid = 16928154 | doi = 10.2165/00003088-200645090-00005 }}</ref><ref name="pmid18043691">{{cite journal | vauthors = Johnson TN, Tucker GT, Rostami-Hodjegan A | title = Development of CYP2D6 and CYP3A4 in the first year of life | journal = Clinical Pharmacology and Therapeutics | volume = 83 | issue = 5 | pages = 670–1 | date = May 2008 | pmid = 18043691 | doi = 10.1038/sj.clpt.6100327 | s2cid = 9714442 }}</ref>

Although CYP3A4 is predominantly found in the liver, it is also present in other organs and tissues of the body, where it may play an important role in metabolism. CP3A4 is the major CYP enzyme in the intestine.<ref name="pmid21142260">{{cite journal | vauthors=Seden K, Dickinson L, Khoo S, David D | title=Grapefruit-drug interactions | journal=[[Drugs (journal)|Drugs]] | volume=70 | issue=18 | pages=2373–2407 | year=2010 |  doi = 10.2165/11585250-000000000-00000 | pmid=21142260 }}</ref> CYP3A4 in the intestine plays an important role in the metabolism of certain drugs. Often this allows [[prodrug]]s to be activated and absorbed, as in the case of the [[histamine antagonist|histamine H<sub>1</sub>-receptor antagonist]] [[terfenadine]].

CYP3A4 has also been identified in the brain, but its role in the [[central nervous system]] is unknown.<ref>{{cite journal | vauthors = Robertson GR, Field J, Goodwin B, Bierach S, Tran M, Lehnert A, Liddle C | s2cid = 17209434 | title = Transgenic mouse models of human CYP3A4 gene regulation | journal = Molecular Pharmacology | volume = 64 | issue = 1 | pages = 42–50 | date = July 2003 | pmid = 12815159 | doi = 10.1124/mol.64.1.42 }}</ref>