The cytochrome P450 isoenzymes are a superfamily of enzymes found in the Liver and in all cells except the blood. These enzymes catalyse the metabolism of a large number of endogenous and exogenous compounds-prescription drugs and street drugs.
The vast individual variation of genetics vary greatly according to race and ethnicity. It is the field of PHARMACOGENETICS that accounts for surge in “apparent” mental illness, suicides, drug addiction and homicides and disease susceptibility.
About 5–10% of Caucasians and 0.9% ofAsians metabolise debrisoquine and other substrates of CYP2D6 at a markedly decreased rate. In addition to thepoor and extensive metabolisers, a group called the ultrarapid metabolisers has been identified.
The CYP2C19 enzyme is also associated with genetic polymorphism. Slow metabolisers are found in 2–5% of Caucasians, about20% of the Japanese population, 19% of African Americansand 8% of Africans .