The role of polymorphic cytochrome P450 enzymes in drug design, development and drug interactions with a special emphasis on phenotyping

Inhibitors of some cytochrome P450s (CYPs) are used to design target-specific drugs. CYPs belonging to families 1–4 play important roles in drug metabolism and therapeutics. Some isozymes of CYPs also activate pro-carcinogens into their carcinogenic forms. Approximately 40–50% human CYP-dependent drug metabolism is carried out by polymorphic CYPs resulting in therapeutic failure and adverse reactions. Phenotyping of CYPs involved in the metabolism of a drug is important to understand the potential of clinical interactions and to predict the possible individual variations due to genetic polymorphisms of certain CYPs.