The pharmacogenetics of coumarin therapy

One Rare Warfarin Resistance Case and Possible Mechanism Exploration

One 59-year-old female patient with deep venous thrombosis (DVT) and pulmonary embolism (PE) was treated with 6 mg warfarin once daily as an anticoagulant. Before taking warfarin, her international normalized ratio (INR) was 0.98. Two days after warfarin treatment, her INR did not change from baseline. Due to the high severity of the PE, the patient needed to reach her target range (INR goal = 2.5, range = 2~3) rapidly, so the dose of warfarin was increased from 6 mg daily to 27 mg daily. However, the patient's INR did not improve with the dose escalation, still maintaining an INR of 0.97-0.98. We drew a blood sample half an hour before administering 27 mg warfarin and detected single nucleotide polymorphism for the following genes, which were identified to be relevant with warfarin resistance: CYP2C9 rs1799853, rs1057910, VKORC1 rs9923231, rs61742245, rs7200749, rs55894764, CYP4F2 rs2108622, and GGCX rs2592551. The trough plasma concentration of warfarin was 196.2 ng/mL after 2 days of warfarin administration with 27 mg QD, which was much lower than the therapeutic drug concentration ranges of warfarin (500-3,000 ng/mL). The genotype results demonstrate that the CYP4F2gene has rs2108622 mutation which can explain some aspect of warfarin resistance. Further investigations are necessary to fully characterize other pharmacogenomics or pharmacodynamics determinants of warfarin dose-response in Chinese.

Genetic Factors Influencing Warfarin Dose in Han Chinese Population: A Systematic Review and Meta-Analysis of Cohort Studies

OBJECTIVE

To investigate the association of single nucleotide polymorphisms (SNPs) of various genes known to influence mean daily warfarin dose (MDWD) in the Han Chinese population.

METHODS

The study is a systematic review and meta-analysis. Selected studies retrieved by searching Pubmed, Embase (Ovid), Medline, CNKI, Wanfang data, and SinoMed (from their inception to 31 August 2022) for the cohort studies assessing genetic variations that may possibly influence MDWD in Chinese patients were included.

RESULT

A total of 46 studies including a total of 10,102 Han Chinese adult patients were finally included in the meta-analysis. The impact of 20 single nucleotide polymorphisms (SNPs) in 8 genes on MDWD was analyzed. The significant impact of some of these SNPs on MDWD requirements was demonstrated. Patients with CYP4F2 rs2108622 TT, EPHX1 rs2260863 GC, or NQO1 rs1800566 TT genotype required more than 10% higher MDWD. Furthermore, patients with ABCB1 rs2032582 GT or GG, or CALU rs2290228 TT genotype required more than 10% lower MDWD. Subgroup analysis showed that patients with EPHX1 rs2260863 GC genotype required 7% lower MDWD after heart valve replacement (HVR).

CONCLUSION

This is the first systematic review and meta-analysis assessing the association between single nucleotide polymorphisms (SNPs) of various genes known to influence MDWD besides CYP2C9 and VKORC1 in the Han Chinese population. CYP4F2 (rs2108622), GGCX (rs12714145), EPHX1 (rs2292566 and rs2260863), ABCB1 (rs2032582), NQO1 (rs1800566), and CALU (rs2290228) SNPs might be moderate factors affecting MDWD requirements.

REGISTERED INFORMATION

PROSPERO International Prospective Register of Systematic Reviews (CRD42022355130).

Exploring cardioprotective potential of esculetin against isoproterenol induced myocardial toxicity in rats: in vivo and in vitro evidence

BACKGROUND

Esculetin is a natural coumarin derivative from various plants with multiple pharmacological effects. Hence, the present study was undertaken to explore the cardio protective potential of esculetin against isoproterenol induced myocardial toxicity in rats.

METHODS

The treatment schedule was fixed for 28 days and the rats were divided into five groups of six each. Rats of group I received the normal saline and served as normal control, group II was received ISO (100 mg/kg body weight) for last two consecutive days of the study and served as disease control. Groups III and IV received esculetin 10 and 20 mg/kg body weight respectively once a day per oral for 28 days along with ISO for last two consecutive days of the study. Cardiac biomarkers such as CK-MB and LDH, membrane bound Na+ /K+ ATPases activity, myocardial lysosomal enzymes activity and tissue antioxidants status were estimated in the heart tissue samples. The histopathological changes in the myocardium were also assessed. Further, DPPH assay was done to evaluate the free radicals scavenging potential of esculetin. Cytoxicity assay, intracellular ROS levels by DCFDA assay and m-RNA expression of TNF-α, IL-6 and NF-κB by quantitative RT-PCR in H9c2 cell lines.

RESULTS

The increased levels of CK-MB, LDH, LPO, myocardial lysosomal enzymes and membrane bound Na+ /K+ ATPase levels by ISO administration was significantly increased with concomitant decrease in tissue antioxidant enzymes such as GSH, Catalase, and SOD. Pre-treatment with esculetin for 28 days has significantly decreased the levels of cardiac bio-markers, lysosomal enzymes, membrane bound Na+ /K+ ATPase levels as well as Lipid peroxides which is in contrary to the ISO group. Amelioration of the antioxidant levels were also found in esculetin treated groups. Histopathological examination of heart reveals that myocardial degeneration, mononuclear cell infiltration was noticed in ISO treated rats, whereas the same was restored with esculetin treatment. In H9C2 cell lines esculetin could effectively reduced intracellular ROS inhibition and m-RNA expression of pro-inflammatory cytokines including TNF-α, IL-6 and NF-κB to prevent apoptosis or cell necrosis.

CONCLUSION

The study provides the evidence of cardioprotective potentials of esculetin against isoproterenol induced myocardial infarction by antioxidant and myocardial membrane stabilization along with in vitro protection from arsenic induced ROS cell necrosis or apoptosis in H9C2 cells.

Impact of CYP2C9, VKORC1, ApoE and ABCB1 polymorphisms on stable warfarin dose requirements in elderly Chinese patients

Aim: To analyze the impact of nongenetic factors and gene polymorphisms on warfarin dose requirements in elderly Shanghai Han Chinese patients. Materials & methods: Genotypes of CYP2C9 (rs1799853 and rs1057910), FPGS (rs7856096), ApoE (rs7412 and rs429358), GGCX (rs699664 and rs12714145), EPHX1 (rs4653436, rs1877724, rs1051740 and rs1131873), NQO1 (rs1800566 and rs10517), ABCB1 (rs1045642), VKORC1 (rs9923231) and CYP4F2 (rs2108622) in 214 patients with stable warfarin dose were determined and their demographic characteristics were recorded. Results: Multiple linear regression analysis revealed that VKORC1 rs9923231, CYP2C9*3 rs1057910, ApoE rs7412, age, BMI and concomitant amiodarone could explain 37.0% of the individual variations of daily stable warfarin dose. Conclusion: VKORC1 rs9923231, CYP2C9*3 rs1057910, ApoE rs7412, age, BMI and concomitant amiodarone play an important role in stable dose variation of warfarin in elderly Shanghai Han Chinese patients, whereas ABCB1 rs1045642 is not a significant genetic factor.

Evaluation of the predictive performance of Bayesian dosing for warfarin in Chinese patients

Aim: To evaluate the accuracy and predictive performance of Bayesian dosing for warfarin in Chinese patients. Materials & methods: Six multiple linear regression algorithms (Wei, Lou, Miao, Huang, Gage and IWPC) and a Bayesian method implemented in Warfarin Dose Calculator were compared with each other. Results: Six multiple linear regression warfarin dosing algorithms had similar predictive ability, except Miao and Lou. The mean prediction error of Bayesian priori and posteriori method were 0.01 mg/day (95% CI: -0.18 to 0.19) and 0.17 mg/day (95% CI: -0.05 to 0.29), respectively, and Bayesian posteriori method demonstrated better performance in all dose ranges. Conclusion: The Bayesian method showed a good potential for warfarin maintenance dose prediction in Chinese patients requiring less than 6 mg/day.

A new algorithm to predict warfarin dose from polymorphisms of CYP4F2, CYP2C9 and VKORC1 and clinical variables: Derivation in Han Chinese patients with non valvular atrial fibrillation

Few pharmacogenomic dosing regimens of warfarin have been developed for Chinese patients with non valvular atrial fibrillation (NVAF). The objective of this study was to develop a new algorithm by polymorphisms of CYP2C9, VKORC1 and CYP4F2 to predict the daily stable dose of warfarin in Chinese patients with NVAF. A total of 325 Chinese NVAF patients on stable dose of warfarin with a target international normalised ratio of 1.5 to 3.0 were recruited and divided randomly into two cohorts. CYP2C9*3, VKORC1 –1639, VKORC1 1173 and CYP4F2 were detected by ligase detection reaction method. The new algorithm was developed with multivariate linear regression in cohort 1 (260 patients) and assessed with Pearson Correlation Analysis (PCA) in cohort 2 (65 patients). From 260 enrolled patients, the model (R2 = 51.7%) was developed as: Dose = 3.47 − 0.022 (AGE) + 0.017 (WT) + 0.189 (PTE) − 0.283 (β-blocker) − 0.471 (AMIO) − 0.586 (CYP2C9 *1/*3) − 0.296 (VKORC1 CT) – 0.648 (VKORC1 TT) + 0.219 (CYP4F2 TT). PCA displayed that the algorithm was good (r = 0.658). The residual plots revealed that the predicted doses by the algorithm tend to be overestimated when lower doses were administered to patients and to be underestimated in higher doses. The algorithm developed by us might predict warfarin dose used by Chinese NVAF patients.

Long-term outcomes of elderly patients with CYP2C9 and VKORC1 variants treated with vitamin K antagonists

Essentials The long-term effects of VKORC1 and CYP2C9 variants on clinical outcomes remains unclear. We followed 774 patients ≥65 years with venous thromboembolism for a median duration of 30 months. Patients with CYP2C9 variants are at increased risk of death and non-major bleeding. Patients with genetic variants have a slightly lower anticoagulation quality only.

SUMMARY

Background The long-term effect of polymorphisms of the vitamin K-epoxide reductase (VKORC1) and the cytochrome P450 enzyme gene (CYP2C9) on clinical outcomes remains unclear. Objectives We examined the association between CYP2C9/VKORC1 variants and long-term clinical outcomes in a prospective cohort study of elderly patients treated with vitamin K antagonists for venous thromboembolism (VTE). Methods We followed 774 consecutive patients aged ≥ 65 years with acute VTE from nine Swiss hospitals for a median duration of 30 months. The median duration of initial anticoagulant treatment was 9.4 months. The primary outcome was the time to any clinical event (i.e. the composite endpoint of overall mortality, major and non-major bleeding, and recurrent VTE. Results Overall, 604 (78%) patients had a CYP2C9 or VKORC1 variant. Three hundred and thirty-four patients (43.2%) had any clinical event, 119 (15.4%) died, 100 (12.9%) had major and 167 (21.6%) non-major bleeding, and 100 had (12.9%) recurrent VTE. After adjustment, CYP2C9 (but not VKORC1) variants were associated with any clinical event (hazard ratio [HR], 1.34; 95% confidence interval [CI], 1.08-1.66), death (HR, 1.74; 95% CI, 1.19-2.52) and clinically relevant non-major bleeding (sub-hazard ratio [SHR], 1.39; 95% CI, 1.02-1.89), but not with major bleeding (SHR, 1.03; 95% CI, 0.69-1.55) or recurrent VTE (SHR, 0.95; 95% CI, 0.62-1.44). Patients with genetic variants had a slightly lower anticoagulation quality. Conclusions CYP2C9 was associated with long-term overall mortality and non-major bleeding. Although genetic variants were associated with a slightly lower anticoagulation quality, there was no relationship between genetic variants and major bleeding or VTE recurrence.

Quantitative Assessment of CYP2C9 Genetic Polymorphisms Effect on the Oral Clearance of S-Warfarin in Healthy Subjects

BACKGROUND

Genetic polymorphisms in CYP2C9 account for 10-20% of the variability in warfarin dose requirement. As such CYP2C9 genetic polymorphisms are commonly included in algorithms aimed to optimize warfarin therapy as a way to account for variability in warfarin responsiveness that is due to altered pharmacokinetics. However, most of the currently available pharmacokinetic data were derived from studies among patients on chronic warfarin therapy and therefore suffer from the confounding effects of disease states and drug interactions.

OBJECTIVE

The purpose of the present study was to provide an accurate quantitative estimate of S-warfarin oral clearance (CL_S) among healthy subjects carrying different CYP2C9 genotypes.

METHODS

Single dose of warfarin was administered to 150 non-smokers, age (mean ± SD) 23.3 ± 4.5 years, 60% male, non-obese, healthy subjects. Blood samples were taken for up to 168 h and urine was collected over the entire study period.

RESULTS

Compared with carriers of the wild-type CYP2C9*1/*1 genotype (n = 69), CL_S was reduced by 25, 39 and 47% among heterozygote for CYP2C9*2 (n = 41) CYP2C9*3 (n = 26) and carriers of 2 variant alleles (n = 14), respectively (p < 0.001). The corresponding decrease in the formation clearance of 6 and 7 S-hydroxy-warfarin was 45, 65 and 75%, respectively (p < 0.001).

CONCLUSIONS

The current study provides an estimate concerning the effect of CYP2C9 polymorphisms on S-warfarin pharmacokinetics among healthy subjects. As such it is free of the confounding effects of disease states and drug interactions. Further research is needed to evaluate whether the incorporation of quantitative data obtained in the present study into pharmacogenetic warfarin algorithm may enhance its precision.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier NCT00162474.

Mitochondria-targeted esculetin inhibits PAI-1 levels by modulating STAT3 activation and miR-19b via SIRT3: Role in acute coronary artery syndrome

In this study we explored the microRNAs responsible for the regulation of PAI-1 during LPS-stimulated inflammation in human aortic endothelial cells and subsequently studied the effect of a newly synthesized mitochondria-targeted esculetin (Mito-Esc) that was shown for its anti-atherosclerotic potential, in modulating PAI-1 levels and its targeted miRs during angiotensin-II-induced atherosclerosis in ApoE^-/- mice. LPS-stimulated PAI-1 was accompanied with an upregulation of miR-19b and down-regulation of miR-30c. These effects of LPS on PAI-1 were reversed in the presence of both parent esculetin and Mito-Esc. However, the effect of Mito-Esc was more pronounced in the regulation of PAI-1. In addition, LPS-stimulated PAI-1 expression was significantly decreased in cells treated with Anti-miR-19b, thereby suggesting that miR-19b co-expression plays a key role in PAI-1 regulation. The results also show that incubation of cells with Stattic, an inhibitor of STAT-3, inhibited LPS-stimulated PAI-1 expression. Interestingly, knockdown of SIRT3, a mitochondrial biogenetic marker, enhanced PAI-1 levels via modulation of miR-19b and -30c. Mito-Esc treatment significantly inhibited Ang-II-induced PAI-1, possibly via altering miR-19b and 30c in ApoE^-/- mice. The association between PAI-1, miR-19b and -30c were further confirmed in plasma and microparticles isolated from patients suffering from acute coronary syndrome of various degrees. Taken together, LPS-induced PAI-1 involves co-expression of miR-19b and down regulation of miR-30c, and Mito-Esc treatment by modulating miR-19b and miR-30c through SIRT3 activation, inhibits PAI-1 levels that, in part, contribute to its anti-atherosclerotic effects. Moreover, there exists a strong positive correlation between miR-19b and PAI-1 in patients suffering from ST-elevated myocardial infarction.

Nodular Thyroid Disease and Thyroid Cancer in the Era of Precision Medicine

The management of thyroid nodules, one of the main clinical challenges in endocrine clinical practice, is usually straightforward. Although the most important concern is ruling out malignancy, there are grey areas where uncertainty is frequently present: the nodules labelled as indeterminate by cytology and the extent of therapy when thyroid cancer is diagnosed pathologically. There is evidence that the current available precision medicine tools (from all the "-omics" to molecular analysis, fine-tuning imaging or artificial intelligence) may help to fill present gaps in the future. We present here a commentary on some of the current challenges faced by endocrinologists in the field of thyroid nodules and cancer, and illustrate how precision medicine may improve their diagnostic and therapeutic capabilities in the future.

Influence of coumarin and some coumarin derivatives on serum lipid profiles in carbontetrachloride-exposed rats

In the present study, coumarin and some coumarin derivatives (esculetin, scoparone, and 4-methylumbelliferone) were investigated for their lipid-lowering effect in rats. Male Sprague–Dawley rats (150–200 g) were divided into six groups and each group comprised of five rats. Hepatic injury-dependent hyperlipidemia was induced by carbon tetrachloride (CCl4, 1.25 ml/kg). Coumarin and coumarin derivatives esculetin (35 mg/kg), scoparone (35 mg/kg), 4-methylumbelliferone (35 mg/kg), or coumarin (30 mg/kg) were administered to experimental groups at 12-h intervals. Animals received the derivatives esculetin, scoparone or 4-methylumbelliferone prior to the administration of a single toxic dose of CCl4. Serum total cholesterol (TC), triglyceride (TG), very low-density lipoprotein cholesterol (VLDL-C), and low-density lipoprotein cholesterol (LDL-C) levels significantly increased in CCl4-treated group ( p < 0.05, p < 0.01, p < 0.01, and p < 0.05, respectively), while levels of serum high-density lipoprotein cholesterol (HDL-C) decreased ( p < 0.01). 4-Methylumbelliferone had no recovery effects on serum TC levels, however, significantly prevented CCl4-induced hyperlipidemia by reducing TG and VLDL-C levels ( p < 0.05 and p < 0.05, respectively). In addition, coumarin had no recovery effect on any of the serum lipid parameters against CCl4-induced hyperlipidemia. Among the coumarin derivatives only esculetin and scoparone significantly prevented serum HDL-C in CCl4-induced dyslipidemia. The results from this study indicate that the chemical structure of coumarins plays an important role on the regulation of serum lipid profiles.

Predictors of warfarin-associated adverse events in hospitalized patients: Opportunities to prevent patient harm

BACKGROUND

The optimum international normalized ratio (INR) monitoring frequency for hospitalized patients receiving warfarin is unknown.

OBJECTIVE

Assess relationship between daily versus less frequent INR monitoring and overanticoagulation and warfarin-related adverse events.

DESIGN

Retrospective cohort study using Medicare Patient Safety Monitoring System data.

SETTING

Randomly selected acute care hospitals across the United States.

PATIENTS

Patients hospitalized from 2009 to 2013 for pneumonia, acute cardiac disease, or surgery who received warfarin.

INTERVENTIONS

None.

MEASUREMENTS

(1) Association between frequency of INR monitoring and an INR ≥6.0 or warfarin-related adverse event. (2) Association between the rate of change of the INR and a subsequent INR ≥5.0 and ≥6.0.

RESULTS

Among 8529 patients who received warfarin for ≥3 days, for 1549 (18.2%) the INR was not measured on 2 or more days. These patients had higher propensity-adjusted odds ratios (ORs) of having a warfarin-associated adverse event (OR: 1.48, 95% confidence interval [CI]: 1.02-2.17) for cardiac patients and surgical patients (OR: 1.73, 95% CI: 1.20-2.48), with no significant association for pneumonia patients. Cardiac and pneumonia patients with 1 day or more without an INR measurement had higher propensity-adjusted ORs of having an INR ≥6.0 (OR: 1.61, 95% CI: 1.07-2.41 and OR: 1.92, 95% CI: 1.36-2.71, respectively). A 1-day increase in the INR of ≥0.9 occurred in 621 patients (12.5%) and predicted a subsequent INR of ≥6.0 (positive likelihood ratio of 4.2).

CONCLUSION

Daily INR measurement and recognition of a rapidly rising INR might decrease the frequency of warfarin-associated adverse events in hospitalized patients.

Metabolomics and Personalized Medicine

Current clinical practice strongly relies on the prognosis, diagnosis, and treatment of diseases using methods determined and averaged for the specific diseased cohort/population. Although this approach complies positively with most patients, misdiagnosis, treatment failure, relapse, and adverse drug effects are common occurrences in many individuals, which subsequently hamper the control and eradication of a number of diseases. These incidences can be explained by individual variation in the genome, transcriptome, proteome, and metabolome of a patient. Various "omics" approaches have investigated the influence of these factors on a molecular level, with the intention of developing personalized approaches to disease diagnosis and treatment. Metabolomics, the newest addition to the "omics" domain and the closest to the observed phenotype, reflects changes occurring at all molecular levels, as well as influences resulting from other internal and external factors. By comparing the metabolite profiles of two or more disease phenotypes, metabolomics can be applied to identify biomarkers related to the perturbation being investigated. These biomarkers can, in turn, be used to develop personalized prognostic, diagnostic, and treatment approaches, and can also be applied to the monitoring of disease progression, treatment efficacy, predisposition to drug-related side effects, and potential relapse. In this review, we discuss the contributions that metabolomics has made, and can potentially still make, towards the field of personalized medicine.

Methods for Predicting Warfarin Dose Requirements

BACKGROUND

The aim of this study was to compare the predictive performance of different warfarin dosing methods.

METHODS

Data from 46 patients who were initiating warfarin therapy were available for analysis. Nine recently published dosing tools including 8 dose prediction algorithms and a Bayesian forecasting method were compared with each other in terms of their ability to predict the actual maintenance dose. The dosing tools included 4 algorithms that were based on patient characteristics (2 clinical and 2 genotype-driven algorithms), 4 algorithms based on international normalized ratio (INR) response feedback and patient characteristics (2 clinical and 2 genotype-driven algorithms), and a Bayesian forecasting method. Comparisons were conducted using measures of bias (mean prediction error) and imprecision [root mean square error (RMSE)].

RESULTS

The 2 genotype-driven INR feedback algorithms by Horne et al and Lenzini et al produced more precise maintenance dose predictions (RMSE, 1.16 and 1.19 mg/d, respectively; P < 0.05) than the genotype-driven algorithms by Gage et al and Klein et al and the Bayesian method (RMSE, 1.60, 1.62, and 1.81 mg/d respectively). The dose predictions from clinical and genotype-driven algorithms by Gage et al, Klein et al, and Horne et al were all negatively biased. Only the INR feedback algorithms (clinical and genotype) by Lenzini et al produced unbiased dose predictions. The Bayesian method produced unbiased dose predictions overall (mean prediction error, +0.37 mg/d; 95% confidence interval, 0.89 to -0.15) but overpredicted doses in patients requiring >8 mg/d.

CONCLUSIONS

Overall, warfarin dosing methods that included some measure of INR response (INR feedback algorithms and Bayesian methods) produced unbiased and more precise dose predictions. The Bayesian forecasting method produced positively biased dose predictions in patients who required doses >8 mg/d. Further research to assess differences in clinical endpoints when warfarin doses are predicted using Bayesian or INR-driven algorithms is warranted.

Genotype-Guided Dosing of Coumarin Anticoagulants

Background:

Coumarin anticoagulants (acenocoumarol, phenprocoumon, and warfarin) are generally used for the prevention of stroke in patients with atrial fibrillation or for the therapy and prevention of venous thromboembolism. However, the safe use of coumarin anticoagulants is restricted by a narrow therapeutic window and large interindividual dosing variations. Some studies found that the effectiveness and safety of coumarin anticoagulants therapy were increased by pharmacogenetic-guided dosing algorithms, while others found no significant effect of genotype-guided therapy.

Methods:

Four electronic databases were searched from January 1, 2000, to March 1, 2014, for randomized controlled trials of patients who received coumarin anticoagulants according to genotype-guided dosing algorithms. The primary outcome was the percentage of time that the international normalized ratio (INR) was within the normal range (2.0-3.0). Secondary outcomes included major bleeding events, thromboembolic events, and INR ≥4 events.

Results:

Eight studies satisfied the inclusion and exclusion criteria. Genotype-guided dosing of coumarin anticoagulants improved the percentage of time within the therapeutic INR range (95% confidence interval [CI], 0.02-0.28; P = .02; I2 = 70%). Subgroup analysis was performed after dividing the nongenotype-guided group into a standard-dose group (95% CI, 0.14-0.49; P = .0004; I2 = 50%) and a clinical variables-guided dosing algorithm group (95% CI, −0.07-0.15; P = .48; I2 = 34%). There is a statistically significant reduction in numbers of secondary outcomes (INR ≥4 events, major bleeding events, and thromboembolic events; 95% CI, 0.79-1.00; P = .04). Subgroup analysis of secondary outcomes showed no significant difference between genotype-guided dosing and clinical variables-guided dosing (95% CI, 0.84-1.10; P = .57; I2 = 11%), but genotype-guided dosing reduced secondary outcomes compared with standard dosing (95% CI, 0.62-0.92; P = .006; I2 = 0%).

Conclusions:

This meta-analysis showed that genotype-guided dosing increased the effectiveness and safety of coumarin therapy compared with standard dosing but did not have advantages compared with clinical variables-guided dosing.

One-pot synthesis of functionalized 4-hydroxy-3-thiomethylcoumarins: detection and discrimination of Co2+ and Ni2+ ions

A variety of 4-hydroxy-3-thiomethylcoumarin derivatives were synthesized via a one-pot three-component reaction catalysed by l-proline at room temperature. One of the derivative was used as fluorescence probe to monitor and distinguish Co²⁺ and Ni²⁺.

VKORC1 and CYP2C9 Genotype Variations in Relation to Warfarin Dosing in Korean Stroke Patients

Background and Purpose

Variant alleles of CYP2C9 and VKORC1 account for differences in anticoagulation response. We sought to establish a warfarin dosing formula for individualized target International Normalization Ratio of Prothrombin Times (INRs) using data from single nucleotide polymorphisms (SNPs) in VKORC1 and CYP2C9 in Korean patients.

Methods

Ischemic stroke patients displaying stable target INR for at least 3 months before enrollment were analyzed. Warfarin and vitamin K levels were measured to adjust for confounders. Phenotypes were defined using the 'warfarin response index' (WRI) defined as INR divided by the daily maintenance warfarin dose. We tested SNPs in CYP2C9 (3 sites: 430C>T (rs1799853), 1075A>C (rs1057910), 1076T>C) and VKORC1 (14 sites: 381C>T, 861C>A (rs17880887), 2653G>C, 3673A>G, 5496G>T, 5808T>G (r17882154), 6009C>T, 6484T>C (rs9934438), 6853C>T (rs17886369), 7566T>C, 8767G>C, 8814T>C, 9041G>A (rs17880624), and 9071G>T) using a standard sequencing method. Multivariate linear regression analysis was applied to establish the formula for warfarin dosage.

Results

All 204 patients had excellent drug compliance. The mean INR was 2.22 (+0.56) and mean daily maintenance dose of warfarin was 3.92 mg (+1.54). Patients with low WRI were younger (P<0.001) with high body mass index (P=0.003), high prevalence of wild-type CYP2C9 polymorphism (1075A>C, P<0.001), and six heterozygote SNPs in VRORC1 (P<0.001), which were tightly interlinked (381T>C, 3673G>A, 6484T>C, 6853C>G. 7566C>T, 9041G>A) (r²=1). Based on these data, a warfarin dosing formula was established.

Conclusions

WRI is influenced by age, body mass index and SNPs in VKORC1 and CYP2C9 in Korean stroke patients. The obtained warfarin dosing formula may be clinically applicable.

Evaluation of the biological activity of naturally occurring 5,8-dihydroxycoumarin

5,8-Dihydroxycoumarin (5,8-DHC) was isolated from aerial parts of sweet grass (Hierochloë odorata L.) and screened for antioxidant and genotoxic activities. A clear linear dependency of radical scavenging capacity in DPPH^• and ABTS^•+ assays was determined. 5,8-DHC was very efficient in retarding rapeseed oil oxidation (Oxipress test). TPC (total phenols content) and FRAP (the ability to reduce ferric ion to ferrous ion) assays revealed a somewhat lower antioxidant capacity of 5,8-DHC as compared with gallic acid. Genotoxic activity was tested using different genetic end-points: chromosome aberrations (CAs) and micronuclei (MN) in Wistar rat bone marrow in vivo, CAs and sister chromatid exchanges (SCEs) in human lymphocytes in vitro, and somatic mutations and recombination in Drosophila melanogaster wing cells in vivo. 5,8-DHC did not increase frequency of CAs in rat bone marrow cells, but induced a significant increase of MN. It was slightly mutagenic in the Drosophila melanogaster assay after 120 h of treatment, but not after 48 h of treatment. 5,8-DHC induced both CAs and SCEs in vitro in human lymphocytes in a clear dose-dependent manner. Thus, 5,8-DHC may be classified as weakly genotoxic both in vivo and in vitro.

Pharmacogenetics in cardiovascular disorders: an update on the principal drugs

In the coming years, genomics will impact clinical practice in multiple ways. However, one of the most important applications will be in the determination of the best treatments in personalized medicine. This is, in fact, one of the fields in which genetic variants have already been most successful and useful to clinicians. Here, we briefly review the current state of the art on pharmacogenomics and its applications to modern cardiovascular medicine.

Effect of genetic variants, especially CYP2C9 and VKORC1, on the pharmacology of warfarin

The genes encoding the cytochrome P450 2C9 enzyme (CYP2C9) and vitamin K-epoxide reductase complex unit 1 (VKORC1) are major determinants of anticoagulant response to warfarin. Together with patient demographics and clinical information, they account for approximately one-half of the warfarin dose variance in individuals of European descent. Recent prospective and randomized controlled trial data support pharmacogenetic guidance with their use in warfarin dose initiation and titration. Benefits from pharmacogenetics-guided warfarin dosing have been reported to extend beyond the period of initial dosing, with supportive data indicating benefits to at least 3 months. The genetic effects of VKORC1 and CYP2C9 in African and Asian populations are concordant with those in individuals of European ancestry; however, frequency distribution of allelic variants can vary considerably between major populations. Future randomized controlled trials in multiethnic settings using population-specific dosing algorithms will allow us to further ascertain the generalizability and cost-effectiveness of pharmacogenetics-guided warfarin therapy. Additional genome-wide association studies may help us to improve and refine dosing algorithms and potentially identify novel biological pathways.

Personalized medicine in cardiovascular diseases

Personalized medicine is a novel medical model with all decisions and practices being tailored to individual patients in whatever ways possible. In the era of genomics, personalized medicine combines the genetic information for additional benefit in preventive and therapeutic strategies. Personalized medicine may allow the physician to provide a better therapy for patients in terms of efficiency, safety and treatment length to reduce the associated costs. There was a remarkable growth in scientific publication on personalized medicine within the past few years in the cardiovascular field. However, so far, only very few cardiologists in the USA are incorporating personalized medicine into clinical treatment. We review the concepts, strengths, limitations and challenges of personalized medicine with a particular focus on cardiovascular diseases (CVDs). There are many challenges from both scientific and policy perspectives to personalized medicine, which can overcome them by comprehensive concept and understanding, clinical application, and evidence based practices. Individualized medicine serves a pivotal role in the evolution of national and global healthcare reform, especially, in the CVDs fields. Ultimately, personalized medicine will affect the entire landscape of health care system in the near future.

A Randomized and Clinical Effectiveness Trial Comparing Two Pharmacogenetic Algorithms and Standard Care for Individualizing Warfarin Dosing (CoumaGen-II)

Background—

Warfarin is characterized by marked variations in individual dose requirements and a narrow therapeutic window. Pharmacogenetics (PG) could improve dosing efficiency and safety, but clinical trials evidence is meager.

Methods and Results—

A Randomized and Clinical Effectiveness Trial Comparing Two Pharmacogenetic Algorithms and Standard Care for Individualizing Warfarin Dosing (CoumaGen-II) comprised 2 comparisons: (1) a blinded, randomized comparison of a modified 1-step (PG-1) with a 3-step algorithm (PG-2) (N=504), and (2) a clinical effectiveness comparison of PG guidance with use of either algorithm with standard dosing in a parallel control group (N=1866). A rapid method provided same-day CYP2C9 and VKORC1 genotyping. Primary outcomes were percentage of out-of-range international normalized ratios at 1 and 3 months and percentage of time in therapeutic range. Primary analysis was modified intention to treat. In the randomized comparison, PG-2 was noninferior but not superior to PG-1 for percentage of out-of-range international normalized ratios at 1 month and 3 months and for percentage of time in therapeutic range at 3 months. However, the combined PG cohort was superior to the parallel controls (percentage of out-of-range international normalized ratios 31% versus 42% at 1 month; 30% versus 42% at 3 months; percentage of time in therapeutic range 69% versus 58%, 71% versus 59%, respectively, all P <0.001). Differences persisted after adjustment for age, sex, and clinical indication. There were fewer percentage international normalized ratios ≥4 and ≤1.5 and serious adverse events at 3 months (4.5% versus 9.4% of patients, P <0.001) with PG guidance.

Conclusions—

These findings suggest that PG dosing should be considered for broader clinical application, a proposal that is being tested further in 3 major randomized trials. The simpler 1-step PG algorithm provided equivalent results and may be preferable for clinical application.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00927862.

Therapeutic potential of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion injury-induced acute renal failure in rats

This study was designed to investigate the role of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion (I/R)-induced acute renal failure in rats. Acute renal failure was induced in rats by administration of a single dose of cisplatin (CP) (6 mg/kg, intraperitoneally on day 6) and occlusion of the left renal artery for 45 min (I) and opened for the next 24 h (R). The drug samples of 7,8-dimethoxycoumarin (DMC, 50, 75, and 100 mg/kg) and cyclosporin A (50 μM/kg) were administered orally for six consecutive days. Administration of a single dose of cisplatin and I/R event has significantly raised blood urea nitrogen and creatinine, N-acetyl beta-D: -glucosaminidase, and thiobarbituric acid reactive substances but decreased FrNa, creatinine clearance, reduced glutathione (GSH), mitochondrial cytochrome c oxidase, and adenosine triphosphate levels. Further, pretreatment of DMC (50, 75, and 100 mg/kg, p.o., for six consecutive days) has ameliorated the CP- and I/R-induced biochemical and histopathological changes in a dose-dependent manner. Furthermore, 75 and 100 mg/kg of 7,8-dimethoxycoumarin has shown to possess the significant renoprotective effect similar to that of the cyclosporin A-treated group which served as positive control. Based on the results of the present study, it has been concluded that 7,8-dimethoxycoumarin protects the kidney against the CP and I/R injury via antioxidant, anti-inflammatory, and inactivation of mitochondrial permeability transition pore opening.

Influence of genetics and non-genetic factors on acenocoumarol maintenance dose requirement in Moroccan patients

WHAT IS KNOWN AND OBJECTIVE

Coumarin derivatives such as acenocoumarol represent the therapy of choice for the long-term treatment and prevention of thromboembolic diseases. Many genetic, clinical and demographic factors have been shown to influence the anticoagulant dosage. Our aim was to investigate the contribution of genetic and non-genetic factors to variability in response to acenocoumarol in Moroccan patients.

METHODS

Our study included 114 adult Moroccan patients, receiving long-term acenocoumarol therapy for various indications. Tests for VKORC1 -1639G>A promoter polymorphism (rs9923231), CYP2C9*2 rs1799853, CYP2C9*3 rs1057910, and CYP4F2 rs2108622 alleles were undertaken using Taq Man(®) Pre-Developed Assay Reagents for allelic discrimination. The statistical analysis was performed using the SAS V9 statistical package.

RESULTS AND DISCUSSION

Genotyping showed that the allele frequencies for the SNPs studied were no different to those found in Caucasians population. A significant association was observed between the weekly maintenance dose and the VKORC1 (P = 0·0027) and CYP2C9 variant genotypes (P = 0·0082). A final multivariate regression model that included the target International Normalized Ratio, VKORC1 and CYP2C9 genotypes explained 36·2% of the overall interindividual variability in acenocoumarol dose requirement.

WHAT IS NEW AND CONCLUSION

Our study shows large interindividual variability in acenocoumarol maintenance dose requirement in our population. VKORC1 and CYP2C9 variants significantly affected acenocoumarol dose, in-line with results in other populations. For the Moroccan population, the SNPs that have the largest effect on acecoumarol dose are CYP2C9 rs1799853, CYP2C9 rs1057910 and VKORC1 rs9923231.

Personalized medicine: progress and promise

Personalized medicine is a broad and rapidly advancing field of health care that is informed by each person's unique clinical, genetic, genomic, and environmental information. Personalized medicine depends on multidisciplinary health care teams and integrated technologies (e.g., clinical decision support) to utilize our molecular understanding of disease in order to optimize preventive health care strategies. Human genome information now allows providers to create optimized care plans at every stage of a disease, shifting the focus from reactive to preventive health care. The further integration of personalized medicine into the clinical workflow requires overcoming several barriers in education, accessibility, regulation, and reimbursement. This review focuses on providing a comprehensive understanding of personalized medicine, from scientific discovery at the laboratory bench to integration of these novel ways of understanding human biology at the bedside.

Effect of different C3-aryl substituents on the antioxidant activity of 4-hydroxycoumarin derivatives

The antioxidant activity of 4-hydroxycoumarin synthetic derivatives and 4-methylumbelliferone were determined taking 4-hydroxycoumarin as the reference compound. Six 3-aryl-4-hydroxycoumarin derivatives were synthesized from 4-hydroxycoumarin as precursor in order to evaluate changes in their antioxidant properties due to C3-aryl substituent nature. Free radical scavenging capacities of these compounds against two different species DPPH(·) and ABTS(·+) and the protecting ability towards the β-carotene-linoleic acid co-oxidation enzymatically induced by lipoxygenase were measured. In addition, the relationship between the activities of these molecules against DPPH radical and the bond dissociation energy of O-H (BDE) calculated using methods of computational chemistry was evaluated.

Overview of personalized medicine in the disease genomic era

Sir William Osler (1849-1919) recognized that "variability is the law of life, and as no two faces are the same, so no two bodies are alike, and no two individuals react alike and behave alike under the abnormal conditions we know as disease". Accordingly, the traditional methods of medicine are not always best for all patients. Over the last decade, the study of genomes and their derivatives (RNA, protein and metabolite) has rapidly advanced to the point that genomic research now serves as the basis for many medical decisions and public health initiatives. Genomic tools such as sequence variation, transcription and, more recently, personal genome sequencing enable the precise prediction and treatment of disease. At present, DNA-based risk assessment for common complex diseases, application of molecular signatures for cancer diagnosis and prognosis, genome-guided therapy, and dose selection of therapeutic drugs are the important issues in personalized medicine. In order to make personalized medicine effective, these genomic techniques must be standardized and integrated into health systems and clinical workflow. In addition, full application of personalized or genomic medicine requires dramatic changes in regulatory and reimbursement policies as well as legislative protection related to privacy. This review aims to provide a general overview of these topics in the field of personalized medicine.

Drug interactions with antiretrovirals and warfarin

IMPORTANCE OF THE FIELD

Antiretroviral therapy exhibits significant potential to alter the metabolism of other medications. Warfarin is widely used for the management of clotting disorders and is prone to drug-drug interactions that can result in subtherapeutic anticoagulation or over-anticoagulation.

AREAS COVERED IN THIS REVIEW

The mechanism and clinical significance of drug-drug interactions between warfarin and individual antiretrovirals are discussed. Literature searches were conducted in August of 2009 using multiple databases including Medline (1950 - 2009), EMBASE (1980 - 2009), International Pharmaceutical Abstracts (1970 - 2009) and the Cochrane Database of Systematic Reviews. The following search terms were utilized: warfarin, HIV, antiretroviral, drug interaction, protease inhibitor (PI), non-nucleoside reverse-transcriptase inhibitor (NNRTI), cytochrome P450 (CYP450), CYP2C9 and individual antiretrovirals by name. The manufacturers of PIs and NNRTIs were also contacted regarding unpublished data.

WHAT THE READER WILL GAIN

Clinicians will gain an understanding of the antiretrovirals that are prone to alter warfarin metabolism and the implications for warfarin dose modification.

TAKE HOME MESSAGE

Metabolic interaction between warfarin and antiretrovirals is likely, particularly if NNRTIs or PIs are included in the antiretroviral regimen. Titration of warfarin dose should be conducted on the basis of close monitoring of the international normalized ratio. Empiric warfarin dose modifications should be considered for individual antiretrovirals.

Protective effects of coumarin and coumarin derivatives against carbon tetrachloride-induced acute hepatotoxicity in rats

The comparison of the antioxidant activity of some coumarins with their molecular structure is well determined. However, the protective function of coumarins with various chemical structures against liver toxicity has not yet been well established. Therefore, the aim of this study was to evaluate the possible cytoprotective properties of coumarin and some coumarin derivatives against CCl(4) (carbon tetrachloride)-induced hepatotoxicity. Coumarin (1,2-benzopyrone) and coumarin derivatives esculetin (6,7-dihydroxycoumarin), scoparone (6,7-dimethoxycoumarin) and 4-methylumbelliferone (7-hyroxy-4-methyl) were examined for their protective effect against CCl(4)-induced hepatotoxicity in Male Sprague-Dawley rats. A single toxic dose of CCl(4) (1.25 ml kg(-1), orally) produced liver damage in rats, seen histologically as centrilobular necrosis. Administration of CCl(4) increased serum enzyme levels of aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP). Pre-treatment of rats with esculetin (31.15 mg kg(-1), orally) and scoparone (35 mg kg(-1), orally) significantly prevented CCl(4)-induced increase in serum enzymes, whereas 4-methylumbelliferone (35 mg kg(-1)) and coumarin (30 mg kg(-1)) had no effect against CCl(4)-induced rise in serum enzymes. Morphological findings were consistent with the plasma transaminase observations. Among the coumarin analogs, esculetin, which possesses orthodihydroxy coumarins, showed the strongest protective effect against CCl(4)-induced liver damage, followed by scoparone, 4-methylumbelliferone and coumarin, respectively. The results of this study indicate that the chemical structures of coumarins play an important role in the prevention of liver toxicity.

Genomic and personalized medicine: foundations and applications

The last decade has witnessed a steady embrace of genomic and personalized medicine by senior government officials, industry leadership, health care providers, and the public. Genomic medicine, which is the use of information from genomes and their derivatives (RNA, proteins, and metabolites) to guide medical decision making-is a key component of personalized medicine, which is a rapidly advancing field of health care that is informed by each person's unique clinical, genetic, genomic, and environmental information. As medicine begins to embrace genomic tools that enable more precise prediction and treatment disease, which include "whole genome" interrogation of sequence variation, transcription, proteins, and metabolites, the fundamentals of genomic and personalized medicine will require the development, standardization, and integration of several important tools into health systems and clinical workflows. These tools include health risk assessment, family health history, and clinical decision support for complex risk and predictive information. Together with genomic information, these tools will enable a paradigm shift to a comprehensive approach that will identify individual risks and guide clinical management and decision making, all of which form the basis for a more informed and effective approach to patient care. DNA-based risk assessment for common complex disease, molecular signatures for cancer diagnosis and prognosis, and genome-guided therapy and dose selection are just among the few important examples for which genome information has already enabled personalized health care along the continuum from health to disease. In addition, information from individual genomes, which is a fast-moving area of technological development, is spawning a social and information revolution among consumers that will undoubtedly affect health care decision making. Although these and other scientific findings are making their way from the genome to the clinic, the full application of genomic and personalized medicine in health care will require dramatic changes in regulatory and reimbursement policies as well as legislative protections for privacy for system-wide adoption. Thus, there are challenges from both a scientific and a policy perspective to personalized health care; however, they will be confronted and solved with the certainty that the science behind genomic medicine is sound and the practice of medicine that it informs is evidence based.

Chemical and molecular mechanisms of antioxidants: experimental approaches and model systems

Free radicals derived from oxygen, nitrogen and sulphur molecules in the biological system are highly active to react with other molecules due to their unpaired electrons. These radicals are important part of groups of molecules called reactive oxygen/nitrogen species (ROS/RNS), which are produced during cellular metabolism and functional activities and have important roles in cell signalling, apoptosis, gene expression and ion transportation. However, excessive ROS attack bases in nucleic acids, amino acid side chains in proteins and double bonds in unsaturated fatty acids, and cause oxidative stress, which can damage DNA, RNA, proteins and lipids resulting in an increased risk for cardiovascular disease, cancer, autism and other diseases. Intracellular antioxidant enzymes and intake of dietary antioxidants may help to maintain an adequate antioxidant status in the body. In the past decades, new molecular techniques, cell cultures and animal models have been established to study the effects and mechanisms of antioxidants on ROS. The chemical and molecular approaches have been used to study the mechanism and kinetics of antioxidants and to identify new potent antioxidants. Antioxidants can decrease the oxidative damage directly via reacting with free radicals or indirectly by inhibiting the activity or expression of free radical generating enzymes or enhancing the activity or expression of intracellular antioxidant enzymes. The new chemical and cell-free biological system has been applied in dissecting the molecular action of antioxidants. This review focuses on the research approaches that have been used to study oxidative stress and antioxidants in lipid peroxidation, DNA damage, protein modification as well as enzyme activity, with emphasis on the chemical and cell-free biological system.