Detoxication of drugs is controlled by

Cytochrome p450 enzymes are microsomal enzymes that are involved in phase I metabolism of many drugs, Most of the drugs are metabolized by CYP 3 A4 isoform. Drug metabolizing enzymes The drug-metabolizing enzymes are divided into two types : 1. Microsomal These are located on smooth endoplasmic reticulum primarily in the liver, also in kidney, intestinal mucosa and lungs. Examples are monooxygenase, cytochrome P450, glucuronyl transferase. They catalyze most of the oxidation, reduction, hydrolysis and glucuronide conjugation. They are inducible by drugs, diet and other agencies. 2. Nonmicrosomal These are present in the cytoplasm and mitochondria of hepatic cells as well as in other tissues including plasma. Examples are flavoprotein oxidase, esterases, amidases and conjugases. They catalyze some oxidation and reduction, many hydrolysis and all conjugation except glucuronidation. They are not inducible but many show genetic polymorphism (acetyltransferase, pseudocholinesterase)