CYP3A4

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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.