ABSTRACT
Pharmacogenomics can be defined as the study of the genetic factors that determine drug efficacy and toxicity and is closely allied to the subject of pharmacogenetics, which up to the present has been mainly concerned with the study of the genetics of drug metabolism. The CYP2D6 and CYP2C19 polymorphisms were the main cytochrome P450 polymorphisms whose existence was well established from phenotypic analysis prior to the widespread application of gene cloning and other molecular biology techniques to this area. Drug metabolism often proceeds in two phases termed phase I and phase II and typically involves an initial phase I oxidation reaction which facilitates a subsequent phase II conjugation reaction. An ability to predict likely response to particular drugs on the basis of patient genotype would be helpful in determining the most appropriate drug to prescribe. Optimizing the drug treatment of schizophrenia remains difficult with both disease resistance to treatment with anti-psychotic drugs and toxicity problems with these agents common.
