CYP3A4

(redirected from Cytochrome P450 3A4)

CYP3A4

A gene on chromosome 7q21.1 that encodes a member of the cytochrome P450 superfamily of monooxygenases, which catalyse reactions in drug metabolism and synthesis of cholesterol, steroids and other lipids. CYP3A4 localises to the endoplasmic reticulum; its expression is induced by glucocorticoids and drugs. It metabolises roughly half of the drugs in current use today—e.g., paracetamol (acetaminophen), codeine, cyclosporin A, diazepam and erythromycin—as well as steroids and carcinogens.

CYP3A4

One isoenzyme form of the cytochrome P450 system involved in the metabolism of many drugs. Drugs that alter this enzyme system can influence the metabolism of other agents taken by patients and cause unanticipated toxic effects.
References in periodicals archive ?
2004) The structure of human microsomal cytochrome P450 3A4 determined by X-ray crystallography to 2.
Sildenafil and vardenafil both are metabolised primarily in the liver via the cytochrome P450 (CYP) pathway, mostly by CYP 3A4 and to a lesser extent by CYP 2C9, while tadalafil is metabolised almost solely by the cytochrome P450 3A4 [13, 14].
Camptothecin attenuates cytochrome P450 3A4 induction by blocking the activation of human pregnane X receptor.
Differential inhibition of cytochrome P450 3A4, 3A5 and 3A7 by five human immunodeficiency virus (HIV) protease inhibitors in vitro.
The 5'-hydroxymethyl metabolite of flucloxacillin, generated by cytochrome p450 3A4, has also been shown in vitro to be directly toxic to biliary epithelium.
One possible explanation for this difference is that there is a 37% higher clearance rate of amiodarone in females than in males because of differences in cytochrome P450 3A4 activity and the percentage of body fat," the authors reported (Cancer 2013 April 8 2013 [doi.
ONMEL[TM], a potent cytochrome P450 3A4 isoenzyme system (CYP3A4) inhibitor, may increase plasma concentrations of drugs metabolized by this pathway.
There are several factors common to drugs that interact with grapefruit: they are all taken by mouth, the have low to intermediate bioavailability 6 meaning only a fraction of the drug will circulate in the bloodstream, with the rest digested 6 and all of them are broken down by an enzyme called cytochrome P450 3A4, also known as CYP3A4.
In this particular case, busulfan is a substrate of cytochrome P450 3A4, and therefore its pharmacokinetics will be dependent to some degree on the genetic variation in this enzyme.
Although the precise mechanism is not known, it is related to amiodarone's inhibition of the cytochrome P450 3A4 (CYP3A4) enzyme, which also metabolizes simvastatin, a HMG-CoA reductase inhibitor, according to the FDA.
GB 2 395 718 B covering the use of the crystal structure of human cytochrome P450 3A4 granted on 19th January 2005

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