CYP3A drug-metabolizing enzymes

CYP3A is usually considered the most important of all drug-metabolizing enzymes as it accounts for nearly 40% of the total CYP enzymes expressed in the liver [15] and... 

The enzymes of the cytochrome P 4503A family are the predominant phase I drug metabolizing enzymes in man. The major isoform of the CYP3A family is CYP3A4, the predominant form found in adult human liver and small intestine. Members of the 3A4 family are estimated to be responsible for the metabolism of more than one half of all drugs that are substrates... 

The activity of CYP3A isoenzymes in the human fetal liver is similar to that seen in adult liver microsomes. The fetal activity for CYP3A7 isoenzyme is unusual as most other fetal isoenzymes of CYP450 exhibit 5 to 40% of fhe adulf isoenzymes. Fetal and neonatal drug-metabolizing enzyme activities may differ from those in the adult. 

Induction of drug-metabolizing enzymes CYP2D6 and CYP3A was observed in rats administered dong quai extracts (Tang et al. 2006). 

Research was conducted on a proprietary Echinacea purpurea extract, identified as an 8 1 extract of fresh E. purpurea root and flower. In healthy volunteers orally administered 8 mg midazolam (a substrate of GYP3A) and 120 mg fexofenadine (a substrate of P-gp) before and after administration of 1500 mg per day of this extract for 14 days, a decrease in plasma levels (AUCq. ) of midazolam was observed, suggesting induction of the drug metabolizing enzyme CYP3A. 

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