CYP2D6(Cytochrome P450 2D6) is also named as CYP2DL1 and belongs to the cytochrome P450 family. It is a monooxygenase that involved in the metabolism of drugs such as antiarrhythmics,adrenoceptor antagonists,and tricyclic antidepressants. CYP2D6 is responsible for the metabolism of many drugs and environmental chemicals that it oxidizes. It has 2 isoforms produced by alternative splicing with the molecular weight of 56 kDa and 50 kDa.