Promising investigations are being done in the field of pharmacogenetics in order to link altered drug response to heredity and ultimately determine individually tailored drug therapy (i.e. proper drug, dose and treatment strategy) for each patient. Personal differences in response to therapeutic agents and drug toxicity are quite common in clinical practice. For example, 30% of the schizophrenic patients treated with antipsychotic drugs and 35% of the heart patients receiving ß-blockers do not respond to the therapy at all. On the other hand, only one third of the multiple sclerosis patients respond to interferon treatment. Although, multiple factors including lifestyle, diet, and environment change drug response, the key determinants are genetic differences or polymorphisms among individuals. Polymorphic genes encoding drug metabolizing enzymes, transporters, receptors and other drug targets have been found to influence the therapeutic effectiveness and toxicity of many drugs available in medicine. Therefore, the main objective of pharmacogenetics is to develop concepts in order to maximize drug's efficiency while significantly minimizing its adverse reactions based on predetermined interindividual genetic differences
