Application of the Polymorphism of the CYP Genes to the Therapeutic Management and Counseling of Patients.

In recent years, genome science has undergone radical changes and numerous advances have led to the development of its use in medical practice. In particular developments in pharmacogenetics have demonstrated that genetic polymorphism is responsible for inter-individual differences in the drug metabolism. This study was conducted to identify the genetic polymorphisms of CYP 2C 9 and CYP 2 C19 using PCR-RFLP, and the application of a gene analysis was investigated in TDM or pharmaceutical management and in counseling services for patients. In a patient with the following pharmacokinetic parameters for phenytoin, for Km=6.69 μg/mL and Vmax = 3.62 mg/day/kg, and a largely decreased metabolic activity of CYP 2 C9 compared to the general population, the genetic differences in CYP 2 C9 could be determined in genomic DNA based on the patient's peripheral blood. Based on this finding, the effective dose for medication was calculated and administered to the patient. In addition, during medical consultations, both written and oral information in an easily comprehensible form could be given to patients with genetic polymorphism. These procedures allow a for the careful matching of the patient to the right medication and dose. This study indicates the possible application of a genetic analysis of CYP to “Evidence-Based Medicine” in the field of pharmaceutical management in order to control the dosage in individuals and to improve patient counseling.