Identifying drugs needing pharmacogenetic monitoring in a Korean hospital

Purpose. A decision matrix for identifying drugs for which pharmacogenetic drug monitoring (PDM) provides the greatest benefit in a Korean setting is described. Summary. We developed a decision matrix including the ethnic frequency of clinically relevant polymorphic cytochrome P-450 (CYP) enzymes, and the metabolic profiles and adverse drug reactions of drugs. Using the developed decision matrix based on the population allele frequencies of CYP enzymes, we identified potential candidates for PDM among the most commonly used drugs at Seoul National University Hospital (SNUH). Collectively, 17 of these drugs were largely metabolized by at least one polymorphic CYP enzyme. Pharmacogenetic information was used to, identify CYP2C9, CYP2C19, and CYP2D6 as the major CYP enzymes of clinical importance for pharmacologic effect and safety in Koreans. The frequencies of poor and intermediate metabolizers among Koreans were 0% and 2.3-12% for CYP2C9,12% and 42% for CYP2C19, and 0.44% and 28% for CYP2D6, respectively. The frequency of ultrarapid metabolizers of CYP2D6 was 2.28%. The decision matrix and pharmacogenetic information were used to identify seven drugs for PDM: warfarin, glimepiride, diazepam, amitriptyline, nortriptyline, codeine, and oxycoclone. This approach can be applied to other institutional hospitals or other ethnic populations and would be helpful for advancing pharmacy practice. Further work is required to assess the practical and potential clinical relevance of pharmacogenetic variations on drugs of interest before the implementation of PDM. Conclusion. A decision matrix helped identify drugs for which PDM provides the greatest potential benefit at one Korean hospital.