(Phys.org)—Drug design involves guided trial-and-error. How the body metabolizes a particular drug is important for determining drug efficacy. There have been many studies to understand how xenobiotics interact with cytochrome P450s, an important class of enzymes in drug metabolism, but little research has been done to understand aldehyde oxidase (AOX) metabolism. AOX, located in the liver, plays an important role in drug metabolism; however, many potential drugs end up failing during late-stage trials because of their interaction with AOX.