ABSTRACT
Recent data indicate that the discovery and development of a new drug costs around $1 billion, and it may take approximately 10 years for the drug to reach the marketplace [1]. Considering these staggering numbers, it is critical that efforts are made to reduce attrition of drug candidates during the various stages of drug discovery and development. One of the sources of attrition can be inappropriate drug disposition characteristics. Drugs are xenobiotics to living organisms, which therefore biotransform them to less toxic, less active, and more hydrophilic forms and so enhance their excretion in urine. However, biotransformation can also lead to some unwanted consequences, such as rapid clearance of the drug from the body, formation of active metabolites, drug-drug interactions due to enzyme induction or competition, and formation of reactive or other toxic metabolites [2].
