Drug metabolizing enzymes Widespread genetic polymorphism; According to their ability to metabolize drugs,they are classified as: UM,ultra-rapid metabolizer EM,extensive metabolizer IM,intermediate metabolizer PM,poor metabolizer Widespread genetic polymorphism; According to their ability to metabolize drugs, they are classified as: Drug metabolizing enzymes UM, ultra-rapid metabolizer EM, extensive metabolizer IM, intermediate metabolizer PM, poor metabolizer