[Clinical significance of cytochrome P450 genetic polymorphism--part IV. Cytochrome P450 3A4 and 3A5].

The enzymes of cytochrome P450 3A subfamily are responsible for the metabolism of about 50% of commonly used drugs. High inter-individual variability in the activities of these enzymes has been described. The last fourth part of this review focuses on the influence of genetic polymorphism of CYP3A4 and CYP3A5 enzymes on drug effect.