Cytochrome P450 (CYP450) enzymes
Cytochrome P450 enzymes - a group of about 60 endogenous enzymes (enzymes the body produces) that participate in the METABOLISM of drugs. The CYP450 enzymes also participate in lipid (notably cholesterol) and steroid HORMONE synthesis. Most of the CYP450 enzymes that are active in DRUG metabolism are in the LIVER and the SMALL INTESTINE. The CYP450 enzymes function as catalysts to facilitate the processes by which the drug transforms from its initial chemical structure to the biochemical forms that have action in the body. Each of the CYP450 subtypes, also called isoforms or isoenzymes, metabolizes certain drugs or groups of drugs.
Hormones, antibodies, and foods affect the activity of CYP450 enzymes. Interactions among them may block or enhance a drug’s activities; these effects may be beneficial or harmful. Some drug treatment regimens for complex conditions such as HIV/AIDS work by manipulating CYP450 enzyme activity to take advantage of beneficial interactions. Harmful interactions may manifest as adverse drug reactions such as toxicity or unpleasant side effects.
Individuals may express CYP450 activity differently that is, known variation exists among individuals in the ways CYP450 enzymes function. These variations in CYP450 expression factor into individual responses to medications, at least partially accounting for why one drug may be more or less effective than another drug in the same drug family for a particular individual.
See also ALCOHOL INTERACTIONS WITH MEDICATIONS; ANTIBODY; PHARMACODYNAMICS; PHARMACOKINETICS.