Humans ; Warfarin/therapeutic use* ; Cytochrome P-450 CYP2C9/genetics* ; Anticoagulants/therapeutic use* ; Genotype ; Heart Valves ; China ; Apolipoproteins E/genetics* ; Dose-Response Relationship, Drug ; Receptors, Calcitriol/genetics*

OBJECTIVE: To compare the accuracy of five warfarin-dosing algorithms and warfarin stable dose model (2.5 mg/day) for Shandong population. METHODS: One hundred and twenty five patients who achieved stable warfarin dose were enrolled. Clinical and genetic data were used to evaluate the value of each algorithm by calculating the percentage of patients whose predicted warfarin dose was within 20% of the actual stable therapeutic dose and mean absolute error (MAE). RESULTS: The frequency of patients with CYP2C9*1/*1, CYP2C9*1/*3 and CYP2C9*1/*2 genotype was 92.00%, 7.20%, 0.80%, respectively. That of VKORC1-1639 AA, AG and GG genotype was 82.40%, 15.20%, 2.40%, respectively. CYP4F2*1/*1, *1/*3, *3/*3 genotype was 50.40%, 39.20%, 10.40%, respectively. With the same genotypes for other loci, patients who carried at least one VKORC1-16398G mutant allele had increased warfarin stable daily dose compared with VKORC1-1639AA. Compared with CYP4F2*1/*1, those carrying at least one CYP4F2*3 mutant allele had warfarin stable daily dose increased by 5.9%-13.00%. The percentage of ideal prediction calculated from IWPC model (59.20%), Huang model (57.60%) and Ohno model (52.80%) were higher than others. The MAE were 0.35 (95%CI: 0.11-0.49), 0.15 (95%CI: 0.10-0.32), 0.39 (95%CI: 0.12-0.51), respectively. CONCLUSION The polymorphisms of CYP2C9, VKORC1 and CYP4F2 genes can influence the stable dose of warfarin in Shandong population. IWPC algorithm is suitable for guiding the use of warfarin in this population.
Anticoagulants ; administration & dosage ; Aryl Hydrocarbon Hydroxylases ; Cytochrome P-450 CYP2C9 ; genetics ; Cytochrome P450 Family 4 ; genetics ; Dose-Response Relationship, Drug ; Genotype ; Humans ; Models, Theoretical ; Polymorphism, Genetic ; Vitamin K Epoxide Reductases ; genetics ; Warfarin ; administration & dosage

The incidence of polypharmacy-which can result in drug-drug interactions-has increased in recent years. Drug-metabolizing enzymes and drug transporters are important polypharmacy modulators. In this study, the effects of bosentan and rifampin on the expression and activities of organic anion-transporting peptide (OATP) and cytochrome P450 (CYP450) 2C9 and CYP3A4 were investigated in vitro. HEK293 cells and primary human hepatocytes overexpressing the target genes were treated with bosentan and various concentrations of rifampin, which decreased the uptake activities of OATP transporters in a dose-dependent manner. In primary human hepatocytes, CYP2C9 and CYP3A4 gene expression and activities decreased upon treatment with 20 μM bosentan+200 μM rifampin. Rifampin also reduced gene expression of OATP1B1, OATP1B3, and OATP2B1 transporter, and inhibited bosentan influx in human hepatocytes at increasing concentrations. These results confirm rifampin- and bosentan-induced interactions between OATP transporters and CYP450.
Cytochrome P-450 CYP2C9 ; Cytochrome P-450 CYP3A ; Cytochrome P-450 Enzyme System* ; Cytochromes* ; Gene Expression ; HEK293 Cells ; Hepatocytes* ; Humans* ; In Vitro Techniques ; Incidence ; Organic Anion Transporters ; Polypharmacy ; Rifampin*

Pharmacogenetic testing for clinical applications is steadily increasing. Correct and adequate use of pharmacogenetic tests is important to reduce unnecessary medical costs and adverse patient outcomes. This document contains recommended pharmacogenetic testing guidelines for clinical application, interpretation, and result reporting through a literature review and evidence-based expert opinions for the clinical pharmacogenetic testing covered by public medical insurance in Korea. This document aims to improve the utility of pharmacogenetic testing in routine clinical settings.
Anticoagulants/therapeutic use ; Antidepressive Agents/therapeutic use ; Antimetabolites, Antineoplastic/therapeutic use ; Antitubercular Agents/therapeutic use ; Arylamine N-Acetyltransferase/genetics ; Coronary Artery Disease/drug therapy/genetics ; Cytochrome P-450 CYP2C19/genetics ; Cytochrome P-450 CYP2C9/genetics ; Cytochrome P-450 CYP2D6/genetics ; Depressive Disorder/drug therapy/genetics ; Genotype ; Isoniazid/therapeutic use ; Laboratories, Hospital/standards ; Methyltransferases/genetics ; Pharmacogenomic Testing/*methods/standards ; Platelet Aggregation Inhibitors/therapeutic use ; Pulmonary Embolism/drug therapy/genetics ; Ticlopidine/analogs & derivatives/therapeutic use ; Tuberculosis/drug therapy/genetics ; Vitamin K Epoxide Reductases/genetics ; Warfarin/therapeutic use

Talniflumate is a phthalidyl ester of niflumic acid, which has potent analgesic and anti-inflammatory effects and is widely used to treat inflammatory disorders, such as rheumatoid arthritis. To screen the possible genetic factors affecting the pharmacokinetics (PK) of talniflumate, 23 male Korean volunteers were enrolled from two separate bioequivalence studies. All subjects received 740 mg (two tablets) talniflumate in a standard 2×2 cross-over model in a randomized order. For the genetic study, PK parameters of the reference drug were used. We used Illumina Human610Quad v1.0 DNA Analysis BeadChip for whole genome single nucleotide polymorphism (SNP) analysis and whole genome genotyping data were processed by linear regression analysis for PK parameters. Whole genome analysis revealed 1498 significant SNPs (P < 0.0001) for Cmax, 65 significant SNPs (P < 0.0001) for T(max), and 1491 significant SNPs (P < 0.0001) for AUC(inf). For clinical pharmacological purposes, we selected SNPs from drug metabolizing enzymes and transporters, and analyzed the PK parameters of various genotypes. Two SNPs (rs11165069 from ABCA4 (p=0.00002); rs17847036 from CYP2C9 (p=0.000001)) showed significant associations with talniflumate C(max). In the T(max) group, two SNPs (rs3787555 from CYP24A1 (p=0.00035); rs2275034 from ABCA4 (p=0.000587)) showed significant associations with talniflumate T(max). In the AUC(inf) group, two SNPs (rs11165069 from ABCA4 (p=0.00002); rs12461006 from SLC1A6 (p=0.00008)) exhibited significant associations with talniflumate absorption. These results show that genetic factors could affect the PK parameters, and provide information that may be used in the development of personalized talniflumate therapy.
Absorption ; Arthritis, Rheumatoid ; Cytochrome P-450 CYP2C9 ; DNA ; Genome ; Genotype ; Humans ; Linear Models ; Male ; Mass Screening* ; Niflumic Acid ; Pharmacogenetics ; Pharmacokinetics* ; Polymorphism, Genetic* ; Polymorphism, Single Nucleotide ; Therapeutic Equivalency ; Vitamin D3 24-Hydroxylase ; Volunteers

Pharmacogenetics is a rapidly evolving field and the number of pharmacogenetic tests for clinical use is steadily increasing. However, incorrect or inadequate implementation of pharmacogenetic tests in clinical practice may result in a rise in medical costs and adverse outcomes in patients. This document suggests guidelines for the clinical application, interpretation, and reporting of pharmacogenetic test results based on a literature review and the collection of evidence-based expert opinions. The clinical laboratory practice guidelines encompass the clinical pharmacogenetic tests covered by public medical insurance in Korea. Technical, ethical, and regulatory issues related to clinical pharmacogenetic tests have also been addressed. In particular, this document comprises the following pharmacogenetic tests: CYP2C9 and VKORC1 for warfarin, CYP2C19 for clopidogrel, CYP2D6 for tricyclic antidepressants, codeine, tamoxifen, and atomoxetine, NAT2 for isoniazid, UGT1A1 for irinotecan, TPMT for thiopurines, EGFR for tyrosine kinase inhibitors, ERBB2 (HER2) for erb-b2 receptor tyrosine kinase 2-targeted therapy, and KRAS for anti-epidermal growth factor receptor drugs. These guidelines would help improve the usefulness of pharmacogenetic tests in routine clinical settings.
Antidepressive Agents, Tricyclic ; Atomoxetine Hydrochloride ; Clinical Laboratory Services ; Codeine ; Cytochrome P-450 CYP2C19 ; Cytochrome P-450 CYP2C9 ; Cytochrome P-450 CYP2D6 ; Expert Testimony ; Genetic Testing ; Humans ; Insurance ; Isoniazid ; Korea ; Pharmacogenetics ; Protein-Tyrosine Kinases ; Tamoxifen ; Warfarin

PURPOSE: The genes for cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex subunit 1 (VKORC1) have been identified as important genetic determinants of warfarin dosing and have been studied. We developed warfarin algorithm for Korean patients with stroke and compared the accuracy of warfarin dose prediction algorithms based on the pharmacogenetics. MATERIALS AND METHODS: A total of 101 patients on stable maintenance dose of warfarin were enrolled. Warfarin dosing algorithm was developed using multiple linear regression analysis. The performance of all the algorithms was characterized with coefficient of determination, determined by linear regression, and the mean of percent deviation was used to predict doses from the actual dose. In addition, we compared the performance of the algorithms using percentage of predicted dose falling within ±20% of clinically observed doses and dividing the patients into a low-dose group (≤3 mg/day), an intermediate-dose group (3-7 mg/day), and high-dose group (≥7 mg/day). RESULTS: A new developed algorithms including the variables of age, body weight, and CYP2C9 and VKORC1 genotype. Our algorithm accounted for 51% of variation in the warfarin stable dose, and performed best in predicting dose within 20% of actual dose and intermediate-dose group. CONCLUSION: Our warfarin dosing algorithm may be useful for Korean patients with stroke. Further studies to elucidate clinical utility of genotype-guided dosing and find the additional genetic association are necessary.
Aged ; *Algorithms ; Anticoagulants/*administration & dosage/therapeutic use ; Cytochrome P-450 CYP2C9/*genetics ; Dose-Response Relationship, Drug ; Female ; Genotype ; Humans ; International Normalized Ratio ; Linear Models ; Male ; Middle Aged ; Multivariate Analysis ; Pharmacogenetics ; Regression Analysis ; Republic of Korea ; Stroke/*drug therapy/ethnology ; Vitamin K Epoxide Reductases/*genetics ; Warfarin/*administration & dosage/therapeutic use

The study aimed to establish a population pharmacokinetic/pharmacodynamic (PPK/PD) model of warfarin. PCR-RFLP technique was used to genotype the CYP2C9 and VKORC1 polymorphisms of 73 patients. RP-HPLC-UV method was used to determine the 190 plasma concentrations of warfarin. Application of NONMEM, the clinical information and 263 international normalized ratio (INR) monitoring data were used to investigate the effect of genetic, physiological, pathological factors, other medication on clearance and anticoagulant response. The final model of warfarin PPK/PD was described as follows: CL = θCL · (WT/60)θWT · θCYP · eηCL (if CYP2C9*1/*1, θCYP = 1; if *1/*3, θCYP = 0.708); EC50 = θEC50 · θVKOR · eηEC50 (if VKORC1- 1639AA, θVKOR = 1; if GA, θVKOR = 2.01; V = θV; K(E0) = θK(E0); Emax = θEmax; E0 = θE0 · eηE0. Among them, the body weight (WT), CYP2C9 and VKORC1 genotype had conspicuous effect on warfarin PK/PD parameters. The goodness diagnosis, Bootstrap, NPDE verification showed that the final model was stable, effective and predictable. It may provide a reference for opitimizing the dose regimen of warfarin.
Anticoagulants ; pharmacology ; Body Weight ; Cytochrome P-450 CYP2C9 ; genetics ; Genotype ; Humans ; International Normalized Ratio ; Nonlinear Dynamics ; Polymorphism, Genetic ; Vitamin K Epoxide Reductases ; genetics ; Warfarin ; pharmacokinetics

OBJECTIVE To assess the influence of genetic polymorphisms and non-genetic factors on warfarin maintenance dose variations in order to provide guidance for personalized use of warfarin. METHODS Two hundred patients from outpatient and inpatient with stable international normalized ratio(INR) were recruited. Clinical data and blood samples were collected. Genotypes of 4 genes involved in warfarin metabolic pathways were determined with Sanger sequencing. Based on statistical analysis of warfarin maintenance dosage, a mathematical model was established. RESULTS Among non-genetic factors, the age and height have significant influence in warfarin dosage. The dosage is negatively correlated with age but positively correlated with height. The difference in dosage for between the 20-year-old group and 60-year-old group has reached 1.81 mg/day, and that for between the 140 cm in height and 180 cm in height groups has reached 1.06 mg/day. VKORC1 -1639G/A, CYP2C9 430C/T, CYP2C9 1075A/C and CYP4F2 V433M polymorphisms have significant influence on stable warfarin dosage. The dosage for patients with wild type and mutant genotypes has varied from 0.35 mg/day to 0.84 mg/day. CONCLUSION Non-genetic factors and genetic polymorphisms play important roles in personalized variations of warfarin maintenance dose. The establishment of mathematical models considering multiple factors is helpful in evaluating the safety and effectiveness of warfarin dosage.
Adult ; Aged ; Anticoagulants ; administration & dosage ; Cytochrome P-450 CYP2C9 ; genetics ; Cytochrome P-450 Enzyme System ; genetics ; Cytochrome P450 Family 4 ; Female ; Humans ; Male ; Middle Aged ; Polymorphism, Genetic ; Vitamin K Epoxide Reductases ; genetics ; Warfarin ; administration & dosage

A 73-yr-old Korean man with permanent atrial fibrillation visited outpatient clinic with severely increased International Normalized Ratio (INR) values after taking a usual starting dosage of warfarin to prevent thromboembolism. We found out later from his blood tests that he had hyperthyroidism at the time of treatment initiation. His genetic analysis showed CYP2C9*1/*3 and VKORC1+1173TT genotypes. We suspect that both hyperthyroidism and genetic variant would have contributed to his extremely increased INR at the beginning of warfarin therapy. From this case, we learned that pharmacogenetic and thyroid function test might be useful when deciding the starting dosage of warfarin in patients with atrial fibrillation.
Aged ; Anticoagulants/blood/metabolism/therapeutic use ; Aspirin/therapeutic use ; Atrial Fibrillation/*diagnosis ; Chromatography, High Pressure Liquid ; Cytochrome P-450 CYP2C9/*genetics ; Genotype ; Humans ; Male ; Polymorphism, Single Nucleotide ; Tandem Mass Spectrometry ; Thromboembolism/prevention & control ; Thyrotoxicosis/*diagnosis ; Vitamin K Epoxide Reductases/genetics ; Warfarin/*blood/metabolism/therapeutic use