ONCOLOGY Nurse Edition Vol 23 No 2 | Oncology Nurse Edition

The Cytochrome P450 Microenzyme System and Targeted Therapies

February 25, 2009

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.