Type: Abbreviation Definitions: 1. Abbreviation for cytochrome P450 enzymes; usually followed by an arabic numeral, a letter, and another arabic numeral (CYP 2D6). These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions. &nbs... Found on http://www.medilexicon.com/medicaldictionary.php?t=22314