Items in AFP with MESH term: Polymorphism, Genetic
ABSTRACT: Cytochrome P450 enzymes are essential for the metabolism of many medications. Although this class has more than 50 enzymes, six of them metabolize 90 percent of drugs, with the two most significant enzymes being CYP3A4 and CYP2D6. Genetic variability (polymorphism) in these enzymes may influence a patient's response to commonly prescribed drug classes, including beta blockers and antidepressants. Cytochrome P450 enzymes can be inhibited or induced by drugs, resulting in clinically significant drug-drug interactions that can cause unanticipated adverse reactions or therapeutic failures. Interactions with warfarin, antidepressants, antiepileptic drugs, and statins often involve the cytochrome P450 enzymes. Knowledge of the most important drugs metabolized by cytochrome P450 enzymes, as well as the most potent inhibiting and inducing drugs, can help minimize the possibility of adverse drug reactions and interactions. Although genotype tests can determine if a patient has a specific enzyme polymorphism, it has not been determined if routine use of these tests will improve outcomes.
Genetic Factors In Drug Metabolism - Article
ABSTRACT: Patients vary widely in their response to drugs. Having an understanding of the pharmacokinetic and pharmacodynamic properties of various medications is importantwhen assessing ethnic differences in drug response. Genetic factors can account for 20 to 95 percent of patient variability. Genetic polymorphisms for many drug-metabolizing enzymes and drug targets (e.g., receptors) have been identified. Although currently limited to a few pathways, pharmacogenetic testing may enable physicians to understand why patients react differently to various drugs and to make better decisions about therapy. Ultimately, this understanding may shift the medical paradigm to highly individualized therapeutic regimens.
ABSTRACT: Pharmacogenetics is a growing field of research that focuses on the interaction between genetics and drug therapy. Relationships between genetic variation and drug effect have been observed for a growing number of commonly used drugs. Validation studies may soon define the use of these relationships in clinical practice, moving the field toward routine application. Currently, there are only a few pharmacogenetic diagnostic tests available, and clinical guidelines for pharmacogenetically tailored therapy are lacking. It is likely that guidelines for pharmacogenetic dosing of certain commonly used drugs such as warfarin, codeine, and inhaled beta agonists will become available within the next few years.