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

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*

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

<p>AIMTo investigate the influence of cytochrom P450 CYP2C9 polymorphism on the pharmacokinetics of tolbutamide.p><p>METHODSAn oligonucleotide microarray was designed and fabricated to genotype the CYP2C9 accurately and quickly. 137 healthy volunteers were genotyped with the array to investigate the frequency of CYP2C9 functional SNPs. Moreover, 1 homozygous mutant, 9 heterozygous and 10 wild-genotypes subjects in the assay were selected randomly and sequenced directly. After orally taking tolbutamide, blood samples and urine samples were collected, and their pharmacokinetics was studied with HPLC.p><p>RESULTSCYP2C9 *1/*3 were found in 9 of 137 volunteers, CYP2C9 *3/*3 in only one, others were all CYP2C9 *1/*1 wild types. CYP2C9 *2, CYP2C9 *4 and CYP2C9 *5 alleles were not detected. Direct sequencing of the purified PCR products of the heterozygotes, mutant homozygotes and ten wild type individuals gave a corresponding result to that genotyped by microarray. Pharmacokinetic outcome showed that the individuals with CYP2C9 *1/*3 or CYP2C9 *3/*3 had slower metabolic elimination of tolbutamide than those with CYP2C9 *1/*1.p><p>CONCLUSIONCYP2C9 genetic polymorphism has a significant influence on the pharmacokinetics of tolbutamide. Pharmacogenomic study will be helpful in guiding rational and individualized medication. Key words: tolbutamide; cytochrom P450 CYP2C9; allele; single nucleotide polymorphism; genotypingp>
Aryl Hydrocarbon Hydroxylases ; genetics ; Cytochrome P-450 CYP2C9 ; Genotype ; Heterozygote ; Homozygote ; Humans ; Oligonucleotide Array Sequence Analysis ; Polymorphism, Single Nucleotide ; Random Allocation ; Tolbutamide ; pharmacokinetics

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

<p>OBJECTIVESTo establish an algorithm to predict the warfarin maintenance dose in Chinese Han population and validate the accuracy of this algorithm.p><p>METHODSA total of 488 Chinese Han patients, hospitalized in Fuwai hospital and had a stable dose of warfarin and a target international normalized ratio (INR) of 1.5 to 3.0, were recruited. Indications for warfarin use included prosthetic heart valve, atrial fibrillation and pulmonary embolism. These patients were divided into derivation group (n = 323) and validation group (n = 165) according to the enrollment time. A warfarin maintenance dose algorithm was established based on genetic information, demographic characteristics and concomitant medications by multiple linear regression analysis in derivation group. In the validation group, we evaluated the accuracy of our algorithm by comparing the predicted dose with the actual dose.p><p>RESULTSOur algorithm included VKORC1-1639G > A, CYP2C9*3 and CYP4F2 genotype, age, Body hight, body weight, amiodarone and digoxin use (R(2) = 0.652, P < 0.001) .In the validation group, the average predicted dose by our algorithm had no statistical difference with the actual dose [(3.51 ± 1.03) mg vs. (3.53 ± 1.41) mg, P = 0.779]. Our algorithm identified 100 out of 165 (60.6%) patients in the validation group, whose predicted dose of warfarin was within 20% of the actual dose, and predicted warfarin dose was underestimated in 17.6% (29/165) patients and overestimated in 21.8% (36/165) patients.p><p>CONCLUSIONOur algorithm based on VKORC1, CYP2C9 and CYP4F2 polymorphisms can help to predict the warfarin maintenance dose in Chinese Han Population.p>
Adult ; Aged ; Algorithms ; Asian Continental Ancestry Group ; genetics ; China ; Cytochrome P-450 CYP2C9 ; genetics ; Cytochrome P-450 Enzyme System ; genetics ; Cytochrome P450 Family 4 ; Female ; Humans ; International Normalized Ratio ; Male ; Middle Aged ; Models, Theoretical ; Polymorphism, Genetic ; Vitamin K Epoxide Reductases ; genetics ; Warfarin ; administration & dosage ; therapeutic use

<p>OBJECTIVETo investigate the distribution of Warfarin related genes and the relationship between genotype, gender, weight, age and the administrative dose of Warfarin in Shanghai area.p><p>METHODSThe clinical data (including sex, age and administrative dose of Warfarin) of 214 patients with stable warfarin dose and the international normalized ratio (INR) between 1.5-3.0 were collected. Polymerase chain reaction-high resolution melting (PCR-HRM) technique was used to detect the single nucleotide polymorphisms (SNPs) of CYP2C9*2 rs1799853, CYP2C9*3 rs1057910, CYP4F2 rs2108622 and VKORC1 rs9934438. The associations of genotype data with clinical material, including gender, age, weight and warfarin dosage were analyzed.p><p>RESULTSAmong 214 patients, 99.53% (213 cases) patients with CC (wild type) of CYP2C9*2 rs1799853 and only 1 case with CT (heterozygous mutation) ; 92.52% (198 cases) with AA (wild type), 7.48% (16 cases) with CA (heterozygous mutation) of CYP2C9*3rs1057910; about 57.94% (124 cases) with CC(wild type) of CYP4F2 rs2108622, the CT and TT (heterozygous and homozygotic mutation) accounted for 42.06% (90 cases). In SNP VKORC1 rs9934438, 82.71% (177cases) were TT (wild type), 17.29% (37 cases) CT (heterozygous mutation). There are no significant difference (P=0.0872) in patients with maintenance dose in CYP2C9*3 between AA and CA gene mutations[(2.816±1.055) mg/d vs (2.352±0.805)mg/d], and no significant difference (P=0.5954) of that in CYP4F2 between CC and CT+TT gene mutations [(2.736±1.062) mg/d vs (2.813±1.034) mg/d]; but the significant differences (P=0.0001) does exist in patients with maintenance dose in VKORC1 between TT and CT variants [(2.597±0.866) mg/d vs (3.660±1.350) mg/d]. The warfarin maintain dosage was negatively correlated with the average age (r=-0.9669) and positively correlated with the body weight (r=0.9022).p><p>CONCLUSIONIt is of great significance to detect the VKORC1 variants for warfarin dosage adjustment in Shanghai population. However, the detection of CYP2C9*2 and CYP4F2 polymorphisms had no significant associations for warfarin dosage adjustment.p>
Adult ; Aged ; Aged, 80 and over ; Anticoagulants ; administration & dosage ; Body Weight ; China ; epidemiology ; Cytochrome P-450 CYP2C9 ; genetics ; Cytochrome P-450 Enzyme System ; genetics ; Cytochrome P450 Family 4 ; Dose-Response Relationship, Drug ; Female ; Genotype ; Heterozygote ; Humans ; International Normalized Ratio ; Male ; Middle Aged ; Sex Distribution ; Vitamin K Epoxide Reductases ; genetics ; Warfarin ; administration & dosage ; Young Adult

In this study, we successfully expanded a full length gene encoding the monooxygenase eytochrome P450 2C9 gene from human liver of Chinese Han by RT-PCR. Our findings indicated that except G-->T mutation at the 190th nucleotide site, the other nucleotide sequences are completely consistent with CYP2C9 (NM017460) in GenBank. The SDS-PAGE and Western-Blot analysis showed that the CYP 2C9 gene was successfully expressed in the host cell E. coli BL21 (DE3). Our current study lays the foundation for the evaluation of pre-clinical drug metabolism and safety in the future.
Aryl Hydrocarbon Hydroxylases ; biosynthesis ; genetics ; China ; ethnology ; Cloning, Molecular ; Cytochrome P-450 CYP2C9 ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Humans ; Point Mutation ; Polymorphism, Genetic ; Recombinant Proteins ; biosynthesis ; genetics

<p>BACKGROUNDPatients with the genotypes of both CYP2C9*3/*3 and VKORC1-1639 A/A are expected to require the lowest dose of warfarin, and to have a greatly increased risk of bleeding. The experience for the dosing of warfarin in such extremely rare cases has been seldom reported.p><p>METHODSDemographic and clinical data from two cases with stable low dose of warfarin in China were studied by resequencing the corresponding gene segments in their whole blood DNA. The potential clinical value of the pharmacogenetic algorithm for them was evaluated by calculating the stable dose of warfarin in pharmacogenetic algorithm developed by International Warfarin Pharmacogenetics Consortium.p><p>RESULTSBoth cases (68-year-old female and 50-year-old male) were diagnosed as chronic nonvalvular atrial fibrillation needing warfarin treatment, with target international normalized ratio (INR) 2 to 3. Case 1 had stable warfarin dose of 0.625 mg/d and case 2 1.25 mg/d. They needed more than 1 month to stabilize their anticoagulation. Exceeding INR values were recorded for them when the dose of warfarin was no more than 2 mg/d. Hemorrhagic complication appeared in case 1 when the dose was titrated from 2.5 to 1.25 mg/d. No concomitant medicine to increase or decrease the INR value was recorded for them. Genotyping CYP2C9 and VKORC1 showed both patients were the carriers of the homozygous alleles -CYP2C9*3/*3 and VKORC1-1639 A/A. Their stable doses of warfarin calculated by the pharmacogenetic dose algorithm (0.672 mg/d for case 1 and 1.16 mg/d for case 2) were comparable with their actual stable therapeutic doses.p><p>CONCLUSIONSTwo Chinese with the rare genotypes of both CYP2C9*3/*3 and VKORC1-1639 A/A were found to require the extremely low dose of warfarin. The pharmacogenetic algorithm incorporating the variances of VKORC1 and CYP2C9 genotypes, as well as the non-genetic factors could predict their stable dose of warfarin with high accuracy.p>
Aged ; Anticoagulants ; adverse effects ; Aryl Hydrocarbon Hydroxylases ; genetics ; Cytochrome P-450 CYP2C9 ; Female ; Genotype ; Hemorrhage ; chemically induced ; Humans ; Male ; Middle Aged ; Mixed Function Oxygenases ; genetics ; Pharmacogenetics ; Vitamin K Epoxide Reductases ; Warfarin ; adverse effects

<p>OBJECTIVETo assess the contribution of vitamin K epoxide reductase complex 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) genotype, age, body size, height, and weight to warfarin dose requirement.p><p>METHODSBlood samples were collected from 191 patients receiving warfarin therapy. Patients's age, gender, height, and weight were registered. PCR-RFLP method was used for the detection of VKORC1-1639G > A and CYP2C9 genotype.p><p>RESULTSVKORC1-1639G > A genotyping showed that 159 patients were homozygous AA, 31 were heterozygous GA, and 1 was homozygous GG genotype. CYP2C9 genotyping showed that 176 patients were *1/*1, 15 patients were heterozygous *1/*3. Patients with VKORC1-1639 (G > A) GG + GA genotype required a significantly higher warfarin dose than those with AA genotype [(3.36 +/- 0.97) mg/d vs. (1.75 +/- 0.56) mg/d, P < 0.01], and patients with CYP2C9*1/*1 genotype also required a higher warfarin dose than those with CYP2C9*1/*3 genotype [(2.06 +/- 0.83) mg/d vs. (1.55 +/- 1.32) mg/d, P < 0.05]. The multiple linear regression model for warfarin dose indicated age, weight and VKORC1 genotype could explain the inter-individual variation in dose requirement of 9.3%, 7.4%, 51.9% patients, respectively; age, weight, CYP2C9 and VKORC1 genotype together could explain the inter-individual variation in dose requirement of 64.1% patients.p><p>CONCLUSIONThis study showed that age, weight and VKORC1 and CYP2C9 polymorphism had significant influences on warfarin dose requirements and should be considered on dosing regimens modification to improve the safety of warfarin therapy.p>
Adult ; Aged ; Aged, 80 and over ; Anticoagulants ; therapeutic use ; Aryl Hydrocarbon Hydroxylases ; genetics ; Cytochrome P-450 CYP2C9 ; Female ; Genotype ; Humans ; Male ; Middle Aged ; Mixed Function Oxygenases ; genetics ; Polymorphism, Genetic ; Treatment Outcome ; Vitamin K Epoxide Reductases ; Warfarin ; therapeutic use