Microarrays are proving useful in predicting physiological reactions to pharmaceuticals. The cytochrome P450 (CYP) pathway and its variants, particularly CYP2D6 and CYP2C19, are involved in the metabolism of ~25% of all prescription drugs, with antidepressants, antipsychotics, im-munosuppressive, and anticancer drugs being most heavily assessed in this area. If the metabolic status of an individual taking the drugs can be ascertained, many ill effects caused by drug-metabolizing enzymes might be anticipated. Pharmacogenetics might prove useful to help develop such personalized medicine (Evans and Relling, 1999). Microarrays can be utilized to test for CYP polymorphisms, and the data can be used both in the study of disease pathophysiology and drug metabolism and toxicology.
The AmpliChip CYP450 from Roche Molecular Diagnostics (Alameda, CA) is a combination of Roche's PCR technology with the GeneChip microarray system from Affymetrix (Santa Clara, CA). It is the first Food and Drug Administration (FDA)-approved microarray molecular diagnostic test for analyzing 29 polymorphisms and mutations of the CYP2D6 gene, and two polymorphisms of the CYP2C19 gene. Such testing is not meant to be a solitary tool that can determine optimum drug dosage. Rather, it is meant to be used along with clinical evaluation and other methods to select the treatment that is best suited for a patient. The results obtained from AmpliChip CYP450, when combined with pharmacotherapy knowledge, could greatly assist with selecting the optimal drug and dosage in individual cases, and may facilitate the development of personalized medicine (Jain, 2005).
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