Warfarin Is Used As An Oral Anticoagulant Biology Essay

Pharmacogeneticss plays an of import function in the safety and effectivity of unwritten decoagulants. Familial polymorphism in warfarin metamorphosis affects warfarin dose demands. Two common allelomorphic discrepancies in the CYP2C9 cistron, CYP2C92 and CYP2C93, encode enzymes that are, approximately 12 % and 5 % severally every bit efficient as the wild-type enzyme that hydroxylates S Coumadin ( Haining et al. , 1996 ; Rettie et al.

, 1994 ) . Carriers of variant allelomorphs are associated with lower Coumadin dose demands and an increased hazard of hemorrhage, peculiarly at the induction of warfarin therapy ( Aithal et al. , 1999 ) . Patients who are homozygous for CYP2C933 require the lowest doses.Recently, the cistron that encodes vitamin K epoxide reductase ( termed VKORC1 ) , the mark enzyme for Coumadin has been cloned and non-synonymous mutants have been found in warfarin immune patients ( Li et al. , 2004 ; Rost et al. , 2004 ) . It was reported that the patients with changing grades of warfarin opposition were carries mutants at least in one transcript of the cistron that encodes vitamin K epoxide reductase complex 1 ( VKORC1 ) .

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More recent findings showed that VKORC1 familial fluctuation have a greater impact than CYP2C9 familial fluctuation on Coumadin dosage discrepancy ( Aquilante et al. , 2006 ) . Haplotype analyses have shown that most of the noncoding individual nucleotide polymorphisms are in strong linkage disequilibrium. Based on haplotypes, single may be divided into two groups, haplotypes, A ( H1 and H2 ) and B ( H7, H8 and H9 ) , which are associated with lower and higher Coumadin dosage demands, severally ( Sconce et al. , 2005 ) .In Caucasian and Asiatic populations, genotype predicts 25 % of the variableness in Coumadin dosage ( Yuan et al. , 2005 ) .

In India a retrospective survey done in Andhra Pradesh population reported that the clinical and familial factors predict 61 % of the variableness in Coumadin dosage demands ( Pavani et al. , 2012 ) , In Malayan Indians it was found that the average day-to-day dosage of Coumadin was significantly higher in American indians compared with the Chinese and Malay patients ( Gan et al. , 2011 ) . These findings raise the possibility that the CYP2C9 and VKORC1 familial discrepancies may change the dose demand in Tamilian population.

To the best of our cognition the survey has been conducted first clip in Tamilian population to happen out the association of familial polymorphism on Coumadin dose demand. Our survey aims to happen out the influence of CYP2C9 familial polymorphisms on Coumadin metamorphosis, plasma Coumadin degrees and to happen out the consequence of CYP2C9 and VKORC1 familial polymorphism on Coumadin dose demand in patients taking Coumadin.

Materials and methods

Study topics

The survey cohort consisted of out- patients having warfarin care therapy at the cardiology clinic and cardio thoracic and vascular surgery clinics in the Jawaharlal Institute of Postgraduate Medical Education and Research ( JIPMER ) infirmary, Pondicherry. All patients received anticoagulation intervention with Coumadin to accomplish an INR in the mark scope of 2 to 3. Patients of age group 18-65 old ages and of either gender were recruited for the survey. Their birth as Tamilian was assessed by their position based on household history of three coevalss in Tamil Nadu and Pondicherry and talking Tamil as their female parent lingua. Written informed consent was obtained from all the patients included in this survey. Institutional moralss commission approved this survey.

Patients with liver or nephritic disfunction or on intervention with drugs that may be CYP2C9 inducers / inhibitors or pregnant and wet adult females, tobacco users and alkies were excluded. Patients ‘ demographic inside informations such as age, sex, tallness, weight, organic structure mass index, continuance of warfarin therapy, high blood pressure and diabetic position were obtained from patients ‘ instance records. Patients with three back-to-back measurings of INR value between 2 and 3.

5, three months after induction of therapy were included for the survey.

2.2 Genotyping for CYP2C9 and VKORC1 -1639G & A ; gt ; A

Five millilitres of venous blood were collected from the survey participants for genotyping. Deoxyribonucleic acid was extracted from the stored cellular fraction by utilizing phenol-chloroform extraction process. Genotyping of CYP2C9 and VKORC1 were carried out in real-time thermo cycler ( 7300 Applied Biosystems ; Life Technologies Corporation, Carlsbad, CA, USA ) utilizing TaqMan SNP genotyping checks ( VKORC1 ( rs9923231 ) assay ID: C__30996661_30, CYP2C92 ( rs1799853 ) ( assay by design ) , CYP2C93 ( rs1057910 ) assay ID: C_27104892_10 ) . The PCR was carried out in extra in a 20-µL i¬?nal volume that contained 10 µL of TaqMan cosmopolitan PCR maestro mix ( 2x ) , 0.5 µL of 20x working stock of SNP genotyping check and 4.

5 µL of genomic DNA diluted in DNAase free H2O and 5µL of MilliQ H2O ( Millipore Corporate Headquarters, Billerica, MA, USA ) . The thermocycler conditions included one rhythm at 50 & A ; deg ; C for 2 min ; one rhythm at 95 & A ; deg ; C for 10 min to trip the AmpliTaq Gold polymerase followed by 40 rhythms of denaturation at 92 & A ; deg ; C for 15 sec and annealing/extension at 60 & A ; deg ; C for 1 min. The allelomorphic favoritism analysis was performed utilizing 7300 SDS package version 1.3.1.

Plasma Coumadin finding

The plasma Coumadin and 7 hydroxy Coumadin were measured by HPLC method with alteration from antecedently published work ( Kulkarni et al.

, 2008 ) .


1. Blood samples and plasma readying for:

Venous blood ( 5 milliliter ) was collected into EDTA tubings from all patients 12 Hs after the last dosage of Coumadin. The plasma was separated by centrifugation of blood samples at 3000 revolutions per minute for 10 proceedingss and stored at70-C until analysis was done.


Materials and reagents fore HPLC check:

Warfarin pure pulverization, 7 hydroxy Coumadin and internal criterion carbamazepine were obtained from Sigma-Aldrich, St. Louis, USA, All organic dissolvers used were HPLC class and purchased from Merck fortes Pvt Ltd, Worli, Mumbai, India. Potassium di H inorganic phosphate and Di Potassium H inorganic phosphate were obtained from S.D.fine- chem Ltd, Mumbai, India. BOND ELUT- C18, 100 milligram, 3 milliliter solid stage extraction cartridges was obtained from Varian, Inc. ,


3. Standard readying:

Stem solution of Coumadin, 7 hydroxy Coumadin and internal criterion carbamazepine was prepared at 1 mg/ml in methyl alcohol. A series of six standard solutions of Coumadin and, 7 hydroxy Coumadin were prepared in drug free human plasma. The standard plasma solution contained 0.05, 0.1, 0.

5, 1.0, 2.5 and 5.0 µg/ml of Coumadin and 7 hydroxy Coumadin, severally. Plasma criterions and QC samples were aliquoted, stored and treated the same manner as patient blood samples.

The solutions for the standard curve were newly prepared before the analysis. For recovery appraisal of the six analytes standard H2O solutions were prepared by thining the standard stock solution in MilliQ H2O to function as 100 % control.

2.3.4. Extraction process

Solid Phase extraction was used to pull out the drug from plasma samples. Ten microliters of 1mg/ml internal criterion ( Carbamazepine ) was added in 1 milliliter criterion, QC and patient plasma samples. C18 cartridges were used for extraction, briefly, the cartridges were conditioned before adding plasma by utilizing 2 milliliter of 1 % methyl alcohol ( pH 2.

8 adjusted with orthophosphoric acid ) . The plasma samples were strictly vortexed and added in the learned columns. The Coumadin and 7 hydroxy Coumadin retained in the column were eluted with 2 milliliters of acetonitrile. The organic stage was transferred to fresh glass tubings and evaporated to dryness under N gas in a H2O bath at 60 & A ; deg ; C in sample evaporator. The samples were reconstituted with 200 µl of MilliQ H2O. Fifty microliter was injected into the HPLC.

2.3.5. Chromatography

The nomadic stage consisted of isopropyl alcohol and K phosphate buffer ( di K H phosphate pH 7.0 adjusted with K di H inorganic phosphate ) . The HPLC system consisted of a Shimadzu LC-10AD VP solvent bringing faculty, Shimadzu SPD-10A VP UV-VIS sensor, 100 µl injection cringle and Hypersil ODS column 4.6 millimeter, 5 millimeter atom size.

The flow rate was maintained at 1 ml/min. The analytes were detected at 308 nanometers, with optical density set at 0.005 Aufs. Separation was performed on a C18 column ( Phenomenex, 150-4.6 millimeter, 5 µm ) . , Coumadin, 7 hydroxy Coumadin and carbamazepine had the keeping clip 3.4 min, 2.

8 min and 8.1 min, severally. The average recoveries of compounds were consistent, at & A ; gt ; 88 % for 7 hydroxy Coumadin and & A ; gt ; 93 % for Coumadin.

The preciseness and duplicability of the check was estimated and was & A ; lt ; 5.37 % for inter-day and & A ; lt ; 6.90 % for intra-day at the concentration 0.1, 0.5, 1.0, 2.5 and 5.0 µg/ml.

All the chromatograms were analyzed by utilizing the package CLASS-VP version 6.14 SP2.

Statistical analysis

GraphPad Instat® version 3.

06 ( San Diego, USA ) and IBM® SPSS® Statistics ( SPSS Inc. , Chicago, IL, USA ) were used for statistical analysis. The genotype frequences were analyzed for Hardy- Weinberg equilibrium. The mean care dosage between the genotype groups were compared by Kruskal Wallis trial and Mann- Whitney trial. Plasma degrees of Coumadin and 7 hydroxy Coumadin between the genotype groups were compared by odd t trial ( Welch corrected ) and warfarin metabolic ratio ( MR ) by the Mann- Whitney trial. The genotype- phenotype relationship was evaluated utilizing additive arrested development analysis. Stepwise multivariate arrested development analysis was used to happen the influence of the independent variables ( age, BMI, attendant medicines, comorbid conditions and familial polymorphisms ) on the dependant variable ( logarithmic transferred day-to-day care dosage ) . P & A ; lt ; 0.

05 was considered statistically important.


The demographic inside informations were obtained from patient instance records ( Table 1 ) . The average mean day-to-day dosage of Coumadin was calculated to be 4.88± 1.

63 mg. Warfarin was prescribed largely for patients with arthritic bosom disease ( mitral stricture ) ( 65.36 % ) .

In our survey, the allele frequences of CYP2C91 ( 91.6 % ) , CYP2C92 ( 2.5 % ) , CYP2C93 ( 5.

9 % ) , were consistent with those reported for the survey population. The G and A allele frequence of VKORC1 were found to be 92.4 % and 7.6 % , severally. The genotype frequences of these discrepancies were found to be in Hardy- Weinberg equilibrium. The day-to-day care dosage in the patients with any variant genotype was significantly lower than the normal genotype ( Table 2 ) . The normal genotypes of CYP2C9 and VKORC1 was found to be similar with the care dosage of Coumadin ( 5.2 mg/day for CYP2C911 and 5.

1 mg/day for VKORC1 GG ) . Patients holding two faulty allelomorphs in CYP2C9 cistron required lower dosage ( 2.5 mg/day ) . The homozygote discrepancy in VKORC1 ( AA ) was found in merely one patient and the day-to-day care dosage was lower ( 3 mg/day ) than the other genotype group.The consequence of combination of variant genotypes on care dosage was compared with the normal genotype combinations ( Table 3 ) . The patients transporting both the variant genotypes were required lower dosage as compared to the any one discrepancy and normal genotype bearers.

Patients with both normal genotypes and transporting both variant genotypes were found to be 75.8 % and 6.7 % ( 12 patients ) , severally.Patients with two variant allelomorphs or one discrepancy allelomorph in CYP2C9 ( 12 and 13 ) had lower 7 hydroxy Coumadin plasma degrees, while 11 bearers had the highest ( Table 4 ) . There was a important difference observed in metabolic ratios between the patients with 11 and 12 or 13 ( P & A ; lt ; 0.05 ) . In univariate and multivariate arrested development analysis it was observed that age ( p & A ; lt ; 0.

05 ) , day-to-day care dosage ( p & A ; lt ; 0.05 ) , CYP2C92 and CYP2C93 genotype ( p & A ; lt ; 0.0001 ) were significantly influenced the Coumadin metabolic ratio. This consequence indicates that the CYP2C9 familial polymorphism influences warfarin metabolic ratio.Linear arrested development analysis revealed a positive correlativity of plasma Coumadin concentration and day-to-day Coumadin dosage ( r2 = 0.24, p=0.016 ) , besides a positive one-dimensionality was observed between plasma Coumadin and 7 hydroxy Coumadin ( r2=0.

47, P & A ; lt ; 0.0001 ) . Due to skewed distribution the day-to-day dosage was converted into logarithmic transformed dosage and was taken into univariate and multivariate analysis, univariate analysis revealed that age significantly act upon the day-to-day dosage ( p & A ; lt ; 0.

05 ) , organic structure weight ( p & A ; lt ; 0.0001 ) , tallness ( p & A ; lt ; 0.05 ) and organic structure mass index ( P & A ; lt ; 0.0001 ) , familial polymorphism in the two cistrons CYP2C92 ( P & A ; lt ; 0.0001 ) , CYP2C93 ( P & A ; lt ; 0.0001 ) , VKORC1-1639G & A ; gt ; A ( P & A ; lt ; 0.05 ) significantly influenced the day-to-day dosage. Multivariate stepwise arrested development analysis was performed by adding all the important factors from univariate analysis ( table 5 ) .

The multivariate analysis revealed that the combined consequence of age, weight and genotype contributes 35.1 % dose fluctuation. Body weight entirely significantly reduces 13.2 % of the care dosage. In our survey 8 ( 4.4 % ) patients were reported to hold hemorrhage hazard. But there was no important association found with the familial polymorphisms and other factors.


The individual base polymorphisms in these cistrons widely varied between the populations ( Margaglione et al. , 2000 ) . There was important difference observed in the different cultural population having coumarin anti-coagulants. It is good documented that the two allelomorphs CYP2C92 ( rs1799852 ) and CYP2C93 ( rs1057910 ) were significantly associated with reduced Coumadin dosage demands ( warfarin sensitiveness ) and higher susceptibleness to o.

d. ( Margaglione et al. , 2000 ) .

A direct association of CYP2C9 genotype anticoagulation position and hemorrhage was foremost reported by Higashi et Al ( Higashi et al. , 2002 ) . Besides the allele frequences of CYP2C92 and CYP2C93 diverge well among different cultural groups ( Stubbins et al. , 1996 ) .

The frequences of CYP2C91, 2 and 3 in the south Indian population were 0.88 ( 95 % CI 0.85- 0.91 ) , 0.

04 ( 95 % CI 0.02-0.06 ) and 0.08 ( 95 % CI 0.06-0.

11 ) , severally ( Jose et al. , 2005 ) . In the present survey the allelomorph and genotype frequences of CYP2C9 was in understanding with the old survey.To the best of our cognition, this survey investigates the genotype- phenotype correlativity of CYP2C9 and Coumadin for the first clip in Tamilian population. The survey besides investigates the influence of familial polymorphism in two cistrons CYP2C9 and VKORC1 on warfarin care dosage. Further, we have investigated the influence of CYP2C9 familial polymorphisms on warfarin metabolic ratio. Higher 7 hydroxy Coumadin degree and lower metabolic ratio were seen in patients with normative allelomorphs. Whereas, lower 7 hydroxy Coumadin and higher metabolic ratio were observed in patients with any one faulty allelomorph.

There was no important difference observed between CYP2C912 and CYP2C913 bearers. The scope of average plasma concentration in the old surveies ( Bentley et al. , 1986 ; Routledge et al. , 1998 ) was reported as 0.8 milligram to 2.4 mg/litter. In our survey the average plasma concentration was found to be 2.

81 mg/liter, and somewhat higher than the normal scope. A pilot survey was conducted antecedently in 25 patients in the North Indians to mensurate average entire plasma Coumadin degrees and it was found to be 3.01±2.48 ( SD ) µg/ml. The average 7 hydroxy Coumadin degree was found to be 0.

20± 0.13 ( SD ) µg/ml. In our survey the average plasma Coumadin was somewhat lower ( 2.81±1.

77 at ( SD ) µg/ml ) and the average plasma 7 hydroxy Coumadin was higher ( 0.68± 0.69 ( SD ) µg/ml ) than the old survey ( Kulkarni et al. , 2008 ) . The higher degrees of average 7- hydroxy Coumadin was observed perchance due to the lower frequence of discrepancies in CYP2C9 cistron in our population.Previous surveies reported that the part of CYP2C92 and CYP2C93 on Coumadin dose finding were found to be 6.

9 % in Malaysians and 7.9 % in Honkong Chinese population ( Lal et al. , 2008 ; Sandanaraj et al. , 2009 ) .

Harmonizing to the CYP2C9 genotype it was observed that the higher care dosage was administered for bearers of CYP2C911 wild type and bearers of variant genotype group received lower care dosage. In our survey the CYP2C92 and CYP2C93 genotypes contributes 16.4 % of dose variableness. Possible ground is that the frequences of CYP2C9 genotypes were more as compared to Chinese and Malayan population. Harmonizing to the VKORC1 genotype, the GG genotype group received higher dosage than the bearers of variant genotype. But in our survey merely one patient was bearer of AA genotype and received 3.0 mg/ twenty-four hours warfarin dosage.

In a recent survey in Italians the bearers of VKORC1 1639 A allelomorph had lower unwritten decoagulant demands ( 4.7, 3.7, 2.2 mg/day for GG, GA, AA genotype severally ; P & A ; lt ; 0.0001 ) , higher mean INR ( 2.7, 2.8, 2.9 ; P = 0.

05 ) and a higher figure of patients with a curative scope than GG genotype bearers ( 17 % vs. 0 % in GG genotype, P = 0.036 ) ( Giansante et al. , 2012 ) . In a recent survey conducted in Malaysia, the mean dosage of Coumadin for all patients was 3.7 milligram, and the average day-to-day dosage of Coumadin was significantly higher in American indians compared with the Chinese and Malay patients, 4.9 versus 3.

5 and 3.3 milligram, severally ( Gan et al. , 2011 ) . The ground for the higher dose demand in Indians was perchance by other factors. Our survey was in understanding with these findings, the mean dosage required in our population was 4.88 mg/day and our population falls under the intermediate dosage group. The ground for this may be that, in our population the more influential VKORC1 -1639 G & A ; gt ; A familial discrepancies are less frequent.

Previous surveies have shown that the VKORC1 familial polymorphisms were a better forecaster than CYP2C9 genotype. In our survey we have observed that the influence of CYP2C92, CYP2C93 ( 16.4 % , P & A ; lt ; 0.0001 ) was higher than VKORC1 ( 3.3 % , P & A ; lt ; 0.05 ) . A possible ground for this may be the lower frequence of VKORC1 discrepancies in the survey population. The old surveies have shown that the day-to-day Coumadin dosage of the survey population does non demo a Gaussian distribution and square root transformed dose were used ( Sconce et al.

, 2005 ; Tham et al. , 2006 ) . However in another old survey it was found that the logarithmic transmutation of the dosage yielded a extremely important trial for Gaussian distribution ( Zhu et al.

, 2007 ) . Similarly, in our survey we have used the logarithmic dosage for arrested development analysis.Following the survey by Sconce et Al ( Sconce et al. , 2005 ) many other surveies have conducted in different cultural populations utilizing multiple additive arrested development analysis technique to foretell the Coumadin care dosage ( Anderson et al. , 2007 ; Gage et al. , 2008 ; Klein et al.

, 2009 ; Pavani et al. , 2012 ; Perini et al. , 2008 ; Schelleman et al. , 2008 ; Wadelius et al. , 2009 ) . Those surveies included covariates such as age, tallness, weight, VKORC1 -1639 G & A ; gt ; A and CYP2C9 genotypes. The inclusion of tallness as a variable had a greater impact in the survey by Sconce et Al ( Sconce et al.

, 2005 ) . Tham et Al ( Tham et al. , 2006 ) found that the age and weight were extremely influential with the familial factors. Weight based dosing of Coumadin is more conventional attack, although, in our survey we have found that weight entirely shows 13.2 % variableness.Previous surveies ( Puehringer et al.

, 2010 ; Schalekamp et al. , 2004 ; Sconce et al. , 2005 ) have explained that age was the 2nd most of import forecaster and shows a greater variableness in dose of coumarin decoagulants. In understanding with the old surveies ( Gage et al. , 2008 ; Kamali et al. , 2004 ) we found that the dose demand cut down with age and shows 3.6 % variableness and associated with important decrease in day-to-day care dosage.

Many surveies have proposed algorithms for ciphering the care dosage and the initial dosage of unwritten decoagulants utilizing the multivariate statistical techniques ( Anderson et al. , 2007 ; Gage et al. , 2008 ; Klein et al. , 2009 ; Sconce et al. , 2005 ; Tham et al.

, 2006 ; Zhu et al. , 2007 ) . In our survey we were able to delegate merely 35.1 % of ascertained inter-individual variableness in Coumadin dosage with regard to the variable factors.

Other than these specific factors extra familial factors, and clinical factors that modify dose demands and therapy. The restriction of our survey was the rigorous exclusion standards for non including the patients with interacting co-medication, comorbidities ( liver and nephritic disfunction ) , alcoholic and tobacco users. It was already known that these factors significantly influence the Coumadin dose demand but the comparative part of familial factors was the premier purpose in our survey.A survey in North Indian patients on intervention with acenocoumarol, explains 41.4 % variableness in dose demand ( Rathore et al. , 2012 ) . They included CYP4F2 and GGCX familial polymorphisms in their algorithm other than CYP2C9 and VKORC1, In Andhra Pradesh population Pavani et Al explained 61 % variableness in dose anticipation based on their algorithm and the survey included CYP4F2 familial polymorphism as extra familial forecaster ( Pavani et al. , 2012 ) .

Several other surveies have been late conducted to place the unknown familial factors act uponing Coumadin ( Cooper et al. , 2008 ; Takeuchi et al. , 2009 ; Wadelius et al. , 2009 ) . It was found that merely VKORC1 and CYP2C9 familial fluctuations were extremely associated with the Coumadin dosage. Additionally merely one SNP in the CYP4F2 cistron was associated with 1-2 % dose variableness. Furthermore extra familial, clinical and environmental factors may significantly lend to better our dosing theoretical account. The present survey provided merely the implicit in clinical and familial fluctuation and their fraction of influence on warfarin day-to-day care dosage in Tamilian population.


The familial fluctuation of CYP2C9 and VKORC1 cistrons were prognostic factors of Coumadin dosage demands in Tamilian population and the influence of CYP2C9 familial fluctuation on Coumadin metamorphosis has been explained. The present survey provided the basic information for developing a pharmacogenetic algorithm for foretelling the initial dosage of Coumadin in Tamilian patients.


This research undertaking was funded by Indian Council of Medical Research ( ICMR ) , New Delhi, India and UMR-775, Bases Mol & A ; eacute ; culaires de la r & A ; eacute ; ponse aux x & A ; eacute ; nobiotiques, INSERM, Universit & A ; eacute ; Paris Descartes, Paris, France. ( Ref. No. INDO/FRC/646/2010-IHD, Dated 10.01.

2012 ) .


Mrs. G.Saraswathi, Ms.S.

Kalaivani, Mrs. Revathy, proficient helpers are appreciatively acknowledged.


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