ONCOLOGY Nurse Edition Vol 23 No 2

The cytochrome P450 microenzyme system has been an important protective system for living things for at least 3 billion years. It is a group or superfamily of isoenzymes that live in the endoplasmic reticulum and mitochondrial membrane of cells, and initially were responsible for detoxifying any poisons that were inhaled or ingested. As a result, these enzymes are found in the nose, saliva, kidneys, and lungs, and in greater numbers in the small intestines and liver. Cytochrome P450s account for about 75% of total metabolism and are important in oxidative metabolism-chemical modification/degradation of drugs.