Pharmacokinetics Of Warfarin Research Articles

Pharmacogenetics of warfarin: A literature review

Warfarin is an oral indirect anticoagulant that is widely used for the prevention of thromboembolic events. Pharmacogenetic testing is the most promising approach to personalizing warfarin treatment. In this review, we aimed to summarize how the patients’ genetic predispositions affect the pharmacokinetics of warfarin, which determines the different dosing regimens for patients. To correctly interpret data in clinical settings, algorithms for selecting the optimal dosing regimen need to be developed that consider the patient’s age, sex, weight, height, health status, and genetic characteristics. These algorithms could help determine the optimal dose, enhance patient adherence to treatment, and increase the physician’s confidence in the treatment safety. Furthermore, although algorithms that consider SNPs in the CYP2C9, VKORC1, and CYP4F2 genes are more effective in predicting warfarin doses, their effectiveness varies according to race.

Molecular Docking of Nigella Sativa L. with PXR Receptors and the Effect of Thymoquinone on PXR Expression in HepG2 Cells

ABSTRACT. The interaction between herbal remedies and drugs is a fascinating phenomenon that might cause therapeutic complications in patients. Warfarin is an anticoagulant drug that provides anti-blood-clotting effects by inhibiting the formation of vitamin K-dependent coagulation factors, and warfarin interacts with the nuclear receptor PXR, subsequently modulating cytochrome P450 during the metabolism process. St. John's wort, an herbal medicine with antidepressant effects, can alter the pharmacokinetics of warfarin. Thymoquinone is one of the active compounds in N. sativa and has pharmacological activities such as anticoagulant, antidiabetic, diuretic, antidepressant, and anti-inflammatory effects. In this study, we investigated the compounds in Nigella sativa (N. sativa) against pregnane X receptor (PXR) and evaluated the impact of thymoquinone (TQ) administration on PXR expression in HepG2 cells. The molecular docking analysis was conducted utilizing the Molecular Operating Environment (MOE) with the PXR (PDB ID: 7AXJ). At the same time, the PXR gene expression was measured using RT-PCR instruments. The RMSD value in docking represents the deviation criteria between the native ligand position and the redocking position result, indicating the capability of MOE and PDB qualification for performing molecular docking. The docking analysis showed that warfarin had the strongest binding energy (7AXJ -6.0507) by forming hydrogen binding type on Arg410. Despite TQ being the major component, it also displayed a high affinity for the two PDB IDs (7AXJ -4.5962). Furthermore, the concurrent administration of warfarin and TQ (19.27 μM) in HepG2 cells showed a significant reduction in the relative mRNA expression of the PXR gene. Given the above-mentioned findings, our study adequately enables us to predict the mechanism behind herb-drug interactions (HDIs) implicating N. sativa, specifically the TQ compound to warfarin metabolism via the activation of the PXR receptor. Keywords: Thymoquinone, expression mRNA, PXR, molecular docking, HepG2 cells.

Interaction between warfarin and selected superfoods: a comprehensive review of potential mechanisms and their clinical significance

Warfarin is one of the oldest and still widely used anticoagulant agents. Interactions between warfarin and herbs have been intensively studied in recent years. However, due to the growing worldwide interest and consumption of herbal products this area requires further investigations. Patients on warfarin should receive special attention from their physicians, especially concerning the concomitant use of herbal products. In this study, we provide a comprehensive review of the mechanisms and clinical significance of interactions between warfarin and selected plants, also frequently referred to as superfoods: Linum usitatissimum, Moringa oleifera, Lindera aggregata, and Nigella sativa. We carried out a non-systematic review of the literature using PubMed using the key terms: warfarin, interaction, Linum usitatissimum, Moringa oleifera, Lindera aggregata, Nigella sativa, CYP2C9, CYP3A4, serum albumin, blood coagulation, antiplatelet. We analyzed articles published up to 2024. The wealth of phytoconstituents contained in reviewed plants favor the occurrence of potential interactions with warfarin. Possible mechanisms involved in these interactions include plasma and platelet hemostasis processes and warfarin pharmacokinetics, i.e. distribution and hepatic metabolism. Critical evaluation of the risk of warfarin-herb interaction is challenging and still inconclusive because most of the sources of evidence are in vitro and animal studies. Therefore we expect human clinical studies evaluating the risk of combined use of warfarin and discussed plants in the near future. To summarize, we hope that the results of our study will help healthcare professionals in their daily practice and improve the safety and effectiveness of warfarin pharmacotherapy.

Effects of Salvianolate Injection on the Pharmacodynamics and Pharmacokinetics of Warfarin in Rats In vivo

Background:: Both Salvianolate Injection and warfarin are widely prescribed in patients with cardiovascular diseases, but the interaction between them is unknown and needs to be investigated. Objective:: This research aims to study the effects and mechanism of Salvianolate Injection on the pharmacodynamics and pharmacokinetics of warfarin in rats. Methods:: Male Wistar rats were intraperitoneally injected Salvianolate Injection (18 mg/kg) with or without oral administration of warfarin (0.2 mg/kg). A coagulation analyzer evaluated prothrombin time (PT) and activated partial thromboplastin time (APTT). International normalized ratio (INR) was calculated based on PT. UPLC-MS/MS combined with a chiral column was used to separate and measure the plasma concentration of R-warfarin and S-warfarin. Agilent SB-C18 column (1.8 μm, 2.1 mm × 50 mm) was used for separation, column temperature at 20°C. The isocratic mobile phase was acetonitrile-aqueous ammonium acetate (5 mM, pH 4) at a flow rate of 0.2 mL/min and 11.5 min for each injection. Pharmacokinetic parameters were calculated using DAS 2.0 software. Results:: Salvianolate Injection increased PT and INR (p < 0.05), while APTT was unaffected (p > 0.05). Compared with the warfarin group, the co-administration of Salvianolate Injection and singledose warfarin enlarged PT and INR (p < 0.05). Similar increases in pharmacokinetic parameters of R-warfarin and S-warfarin, including Cmax, AUC0-t, AUC0-∞, t1/2, and CL/F (p < 0.05), were observed in the co-administration group. A steady-state study of warfarin indicated that PT and INR in the coadministration group are longer than those in the warfarin group (p < 0.05). On days 7th and 8th of warfarin treatment (two and three days after Salvianolate Injection treatment), the plasma concentration of R-warfarin increased by 47.22% and 50.16% (p < 0.05), and plasma concentration of Swarfarin increased by 32.39% and 45.99% (p < 0.05), respectively. Conclusion:: Salvianolate Injection exhibits an anticoagulation effect in rats. Salvianolate Injection can enhance the anticoagulant effect of warfarin by slowing metabolism and increasing the concentration of both enantiomers. These results suggest that the combination of Salvianolate Injection and warfarin should be avoided or closely monitored in case of increasing bleeding risk.

Mechanism of Panax notoginseng saponins modulation of miR-214-3p/NR1I3 affecting the pharmacodynamics and pharmacokinetics of warfarin

BackgroundWith the prevalence of dietary supplements, the use of combinations of herbs and drugs is gradually increasing, together with the risk of drug interactions. In our clinical work, we unexpectedly found that the combination of Panax notoginseng and warfarin, which are herbs that activate blood circulation and remove blood stasis, showed antagonistic effects instead. The purpose of this study was to evaluate the drug interaction between Panax notoginseng saponins (PNS) and warfarin, the main active ingredient of Panax notoginseng, and to explore the interaction mechanism. MethodsThe effects and mechanisms of PNS on the pharmacodynamics and pharmacokinetics of warfarin were explored mainly in Sprague–Dawley rats and HepG2 cells. Elisa was used to detect the concentrations of coagulation factors, HPLC-MS to detect the blood concentrations of warfarin in rats, immunoblotting was employed to examine protein levels, qRT-PCR to detect mRNA levels, cellular immunofluorescence to detect the localization of NR1I3, and dual luciferase to verify the binding of miR-214-3p and NR1I3. ResultsPNS significantly accelerated warfarin metabolism and reduced its efficacy, accompanied by increased expression of NR1I3 and CYP2C9. Interference with NR1I3 rescued the accelerated metabolism of warfarin induce by PNS co-administration. In addition, we demonstrated that PNS significantly reduced miR-214-3p expression, whereas miR-214-3p overexpression reduced NR1I3 and CYP2C9 expression, resulting in a weakened antagonistic effect of PNS on warfarin. Additionally, we found that miR-214-3p bound directly to NR1I3 3′-UTR and significantly downregulated NR1I3 expression. ConclusionOur study demonstrated that PNS accelerates warfarin metabolism and reduces its pharmacodynamics by downregulating miR-214-3p, leading to increased expression of its target gene NR1I3, these findings provide new insights for clinical drug applications to avoid adverse effects.

Evaluation of anticoagulant rodenticide sensitivity by examining in vivo and in vitro responses in avian species, focusing on raptors

Anticoagulant rodenticides (ARs) are used to control pest rodent species but can result in secondary poisoning of non-target animals, especially raptors. In the present study, differences in AR sensitivity among avian species were evaluated by comparing in vivo warfarin pharmacokinetics and effects, measuring cytochrome P450s (CYPs) expression involved in AR metabolism, and conducting in vitro inhibition assays of the AR target enzyme Vitamin K 2,3-epoxide reductase (VKOR). Oral administration of warfarin at 4 mg/kg body weight did not prolong prothrombin time in chickens (Gallus gallus), rock pigeons (Columba livia), or Eastern buzzards (Buteo japonicus). Rock pigeons and buzzards exhibited shorter plasma half-life of warfarin compared to chickens. For the metabolite analysis, 4′-hydroxywarfarin was predominantly detected in all birds, while 10-hydroxywarfarin was only found in pigeons and raptors, indicating interspecific differences in AR metabolism among birds likely due to differential expression of CYP enzymes involved in the metabolism of ARs and variation of VKOR activities among these avian species. The present findings, and results of our earlier investigations, demonstrate pronounced differences in AR sensitivity and pharmacokinetics among bird species, and in particular raptors. While ecological risk assessment and mitigation efforts for ARs have been extensive, AR exposure and adverse effects in predatory and scavenging wildlife continues. Toxicokinetic and toxicodynamic data will assist in such risk assessments and mitigation efforts.

Influence of Quercetin Pretreatment on Pharmacokinetics of Warfarin in Rats.

Warfarin (WAR) is an anticoagulant with a narrow therapeutic index and is principally metabolized by CYP3A4 and CYP2C9 enzymes. The inhibitors of these enzymes may alter the systemic exposure to WAR. Quercetin (QUE), a bioflavonoid, may modify the bioavailability of drugs used concurrently by inhibiting CYP3A4, CYP2C8, CYP2C9, CYP1A2, and Pglycoprotein (P-gp). The current study scrutinized the influence of QUE on WAR pharmacokinetics in rats. QUE was orally administered to animals for 14 consecutive days, followed by WAR as a single oral dose on the 15th day in the pre-treatment group. The co-administration group received a single dose of QUE and WAR concomitantly. Only carboxymethylcellulose (CMC) 0.5% was administered as a vehicle to control group. In the pre-treated group, WAR's Cmax was increased by 30.43%, AUC0-∞ by 62.94%, and t1/2 by 10.54%, while Cl decreased by 41.35%, relative to control. In co-administered animals, WAR's Cmax increased by 10.98%, AUC0-∞ by 20.20%, and t1/2 by 8.87%, while Cl declined by 16.40%. QUE alters the pharmacokinetics of WAR, warranting possibly WAR dose adjustment after confirmatory clinical investigations, specifically in patients with thrombotic disorders and a pre-treatment history of QUE or its product.

Anlotinib and fruquintinib co-administrated with warfarin increases the risk of bleeding: Studied from pharmacokinetic and pharmacodynamic perspectives

BackgroundRecent studies have reported a higher risk of bleeding among patients that are co-administrated with vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR-TKIs) and anticoagulant, which raises our concern about the possible TKIs-warfarin pharmacokinetic and pharmacodynamic interaction that could be life-threatening to tumor patients who take warfarin for preventing deep vein thrombosis (DVT). MethodsInfluences of anlotinib and fruquintinib on the pharmacokinetic and dynamic behavior of warfarin were estimated. Influence on the activity of cytochrome P450 (CYP450) enzymes was detected in vitro through rat liver microsomes. Quantitative analysis of blood concentration in rats was finished by a validated UHPLC-MS/MS method. Furthermore, pharmacodynamic interactions were studied in rats by monitoring prothrombin time (PT) and activated partial thromboplastin time (APTT), while Inferior vena cava (IVC) stenosis-induced DVT model was built to further investigate the antithrombotic effect after co-administration. ResultsAnlotinib inhibited the activity of cyp2c6, cyp3a1/2 and cyp1a2 in rat liver microsomes in a dose-dependent manner, meanwhile enhanced the AUC0∼t and AUC0∼∞ of R-warfarin. However, fruquintinib showed no effects on pharmacokinetics of warfarin. Anlotinib and fruquintinib co-administrated with warfarin was found to exert more significant increase on PT and APTT values than that taking warfarin alone. In IVC stenosis-induced DVT model rats, the co-administration groups significantly reduced the length of thrombus compared with the single warfarin group. ConclusionsAnlotinib and fruquintinib enhanced the anticoagulated and antithrombotic effect of warfarin. The anlotinib-induced interaction may due to the inhibition of the metabolism of warfarin. The mechanism of the pharmacodynamic interaction between fruquintinib and warfarin should be further investigated.

Effects of Enteral Formulas and Their Food Protein and Dietary Fiber Components on Postprandial Plasma Warfarin Concentration in Rats

The purpose of this study was to clarify the effects of enteral formulas and their food protein and dietary fiber components on the pharmacokinetics of warfarin in rats. Blood samples were collected from 0 to 30 h after the oral administration of 0.5 mg/kg warfarin with or without an enteral formula (Mei Balance R®, Mei Flow®, F2 Light®, or PG Soft EJ®), food protein (milk protein or casein), or dietary fiber (indigestible dextrin or carrageenan). Plasma warfarin concentration was determined by liquid chromatography-tandem mass spectrometry. Plasma warfarin concentration was lower at the initial phase after co-administration of F2 Light®, milk protein, or casein compared with the control group, which might have been caused by the suppression of the gastrointestinal absorption of warfarin in accordance with the binding to food protein. Plasma warfarin concentration was significantly higher after co-administration of Mei Flow®, indigestible dextrin, or carrageenan compared with the control group. This is the first study to find that the plasma concentration of warfarin increases when warfarin is co-administered with enteral formula Mei Flow® or their dietary fiber components such as indigestible dextrin or carrageenan. Therefore, close attention should be paid to decreases or increases in the plasma warfarin concentration when warfarin is used with enteral formula.

Predicting in vivo Target Occupancy (TO) Profiles via PBPK-TO Modeling of Warfarin Pharmacokinetics in Blood: Importance of Low Dose Data and Prediction of Stereoselective Target Interactions.

Warfarin is well-recognized for its high-affinity and capacity-limited binding to the pharmacological target and undergoes target-mediated drug disposition (TMDD). Here, we developed a physiologically-based pharmacokinetic (PBPK) model that incorporated saturable target binding and other reported hepatic disposition components of warfarin. The PBPK model parameters were optimized by fitting to the reported blood PK profiles of warfarin with no stereoisomeric separation following oral dosing of racemic warfarin (0.1, 2, 5, or 10 mg) using the Cluster Gauss-Newton Method (CGNM). The CGNM-based analysis yielded multiple "accepted" sets for six optimized parameters, which were then used to simulate the warfarin blood PK and in vivo target occupancy (TO) profiles. When further analyses examined the impact of dose selection on uncertainty in parameter estimation by the PBPK modeling, the PK data from 0.1 mg dose (well below target saturation) was important in practically identifying the target binding-related parameters in vivo When stereoselective differences were incorporated for both hepatic disposition and target interactions, our PBPK modeling predicted that R-warfarin (of slower clearance and lower target affinity than S-warfarin) contributes to TO prolongation following oral dosing of racemic warfarin. Our results extend the validity of the approach by which the PBPK-TO modeling of blood PK profiles can yield TO prediction in vivo (applicable to the drugs with targets of high affinity and abundance and limited distribution volume via non-target interactions). Our findings support that model-informed dose selection and PBPK-TO modeling may aid in TO and efficacy assessment in preclinical and clinical phase-1 studies. Significance Statement The current PBPK modeling incorporated the reported hepatic disposition components and target binding of warfarin and analyzed the blood PK profiles from varying warfarin doses, practically identifying target binding-related parameters in vivo By implementing the stereoselective differences between R- and S-warfarin, our analysis predicted the role of R-warfarin in prolonging overall target occupancy. Our results extend the validity of analyzing blood PK profiles to predict target occupancy in vivo, which may guide efficacy assessment in preclinical and clinical phase-1 studies.

Targeted next-generation sequencing of genes involved in Warfarin Pharmacodynamics and pharmacokinetics pathways using the Saudi Warfarin Pharmacogenetic study (SWAP).

Warfarin is an oral anticoagulant commonly used for treatment and prophylaxis against thromboembolic events. Warfarins's narrow therapeutic index window is one of the main challenges in clinical practice; thus, it requires frequent monitoring and dose adjustment to maintain patients' therapeutic range. Warfarin dose variation and response are attributed to several inter-and intra-individuals factors, including genetic variants in enzymes involved in warfarin pharmacokinetics (PK) and pharmacodynamics (PD) pathways. Thus, we aim to utilize the next-generation sequencing (NGS) approach to identify rare and common genetic variants that might be associated with warfarin responsiveness. A predesigned NGS panel that included 16 genes involved in Warfarin PK/PD pathways was used to sequence 786 patients from the Saudi Warfarin Pharmacogenetic Cohort (SWAP). Identified variants were annotated using several annotation tools to identify the pathogenicity and allele frequencies of these variants. We conducted variants-level association tests with warfarin dose. We identified 710 variants within the sequenced genes; 19% were novel variants, with the vast majority being scarce variants. The genetic association tests showed that VKORC1 (rs9923231, and rs61742245), CYP2C9 (rs98332238, rs9332172, rs1057910, rs9332230, rs1799853, rs1057911, and rs9332119), CYP2C19 (rs28399511, and rs3758581), and CYP2C8 (rs11572080 and rs10509681) were significantly associated with warfarin weekly dose. Our model included genetics, and non-genetic factors explained 40.1% of warfarin dose variation. The study identifies novel variants associated with warfarin dose in the Saudi population. These variants are more likely to be population-specific variants, suggesting that population-specific studies should be conducted before adopting a universal warfarin genotype-guided dosing algorithm.

A Physiological-Based Pharmacokinetic Model Embedded with a Target-Mediated Drug Disposition Mechanism Can Characterize Single-Dose Warfarin Pharmacokinetic Profiles in Subjects with Various CYP2C9 Genotypes under Different Cotreatments.

Warfarin, a commonly prescribed oral anticoagulant medication, is highly effective in treating deep vein thrombosis and pulmonary embolism. However, the clinical dosing of warfarin is complicated by high interindividual variability in drug exposure and response and its narrow therapeutic index. CYP2C9 genetic polymorphism and drug-drug interactions (DDIs) are substantial contributors to this high variability of warfarin pharmacokinetics (PK), among numerous factors. Building a physiology-based pharmacokinetic (PBPK) model for warfarin is not only critical for a mechanistic characterization of warfarin PK but also useful for investigating the complicated dose-exposure relationship of warfarin. Thus, the objective of this study was to develop a PBPK model for warfarin that integrates information regarding CYP2C9 genetic polymorphisms and their impact on DDIs. Generic PBPK models for both S- and R-warfarin, the two enantiomers of warfarin, were constructed in R with the mrgsolve package. As expected, a generic PBPK model structure did not adequately characterize the warfarin PK profile collected up to 15 days following the administration of a single oral dose of warfarin, especially for S-warfarin. However, following the integration of an empirical target-mediated drug disposition (TMDD) component, the PBPK-TMDD model well characterized the PK profiles collected for both S- and R-warfarin in subjects with different CYP2C9 genotypes. Following the integration of enzyme inhibition and induction effects, the PBPK-TMDD model also characterized the PK profiles of both S- and R-warfarin in various DDI settings. The developed mathematic framework may be useful in building algorithms to better inform the clinical dosing of warfarin. SIGNIFICANCE STATEMENT: The present study found that a traditional physiology-based pharmacokinetic (PBPK) model cannot sufficiently characterize the pharmacokinetic profiles of warfarin enantiomers when warfarin is administered as a single dose, but a PBPK model with a target-mediated drug disposition mechanism can. After incorporating CYP2C9 genotypes and drug-drug interaction information, the developed model is anticipated to facilitate the understanding of warfarin disposition in subjects with different CYP2C9 genotypes in the absence and presence of both cytochrome P450 inhibitors and cytochrome P450 inducers.

Warfarin Therapy and Pharmacogenetics

The aim of this work was to review several studies investigating the effects of genetic polymorphisms on warfarin dosing in regional and Iraqi studies and to report any consistent pattern of relevant findings. Despite the growing use of the recently introduced direct oral anticoagulants, warfarin is still the mainstay agent for oral anticoagulation because of its cost-effectiveness. However, a difficulty to establish a stable warfarin dose is frequently encountered. In addition to the warfarin narrow window of efficacy and safety, the main contributor to the challenging dosing is the wide range of variability in warfarin pharmacokinetics and pharmacodynamics among different patients as well as within the single patient context. A link between nonappropriateness of warfarin doses and dramatically increased risk of thromboembolic and hemorrhagic events has been well documented. Several single nucleotide polymorphisms (SNPs) in the genes implicated in warfarin pharmacokinetic and pharmacodynamic processes have been highlighted as possible contributors to warfarin dosing instability. Vitamin K epoxide reductase complex 1 gene SNPs have consistently been found to be the predominant genetic factor contributing the dosing variations. The SNP rs9923231 was significantly associated with the greatest predicting capability of warfarin dosage. However, a range of about 30%–50% of the variances in warfarin dosing was explained by the combined contribution effect of several genetic and nongenetic (clinical) factors in the regional and Iraqi studies.

Intermittent Hypoxia Inhibits Hepatic CYP1a2 Expression and Delays Aminophylline Metabolism.

Purpose In this study, we aimed to determine the effects of intermittent hypoxia (IH) on hepatic cytochrome P450 1A2 (CYP1A2) expression and the pharmacokinetics of CYP1A2-mediated aminophylline and warfarin in vitro and in a rabbit model of obstructive sleep apnea. Materials Human normal liver (LO-2) cells were exposed to 30 min each of 1%, 1–21%, 21%, and 21–1% O2, and then, CYP1A2 expression and drug concentrations were analyzed. We compared the pharmacokinetic parameters of drugs administered to normoxic rabbits and those exposed to 10 min of IH during which the oxygen level fluctuated from 21% to 8%–10% (n = 10 per group). Results. The expression of CYP1A2 protein in vitro was significantly reduced in the IH compared with the normoxic cells (0.56 ± 0.11 vs. 1.27 ± 0.17, p < 0.001). Aminophylline was more abundant in cell culture supernatants after 48 h of IH than in those under normoxia. The T1/2, AUC0–24 h, and Ke values for aminophylline were significantly higher in the IH group. Conclusion Intermittent hypoxia inhibits hepatic CYP1A2 expression and delays aminophylline metabolism, suggesting that the impact of IH on the expression of CYP enzymes should be closely monitored in clinical practice.

Effects and Mechanism of Action of Panax notoginseng Saponins on the Pharmacokinetics of Warfarin.

The interactions between Chinese herbs and drugs pose a great challenge to the combined clinical application of Chinese herbs and drugs. Chinese medicinal products contain complex pharmacologically active components that may influence the in vivo processes of drugs in a variety of ways. In China, drugs based on Panax ginseng total saponins (PNS) are often combined with warfarin for the treatment of cardiovascular diseases. To assess the effects of Panax notoginseng saponins (PNS) on the pharmacokinetics of warfarin and its mechanism. Blood was collected for the determination of the prothrombin time (PT) and international normalized ratio (INR) from rats treated with warfarin alone or with warfarin + PNS. The plasma concentration of warfarin was determined by high-performance liquid chromatography. Western blot was used to detect the expression of cytochrome P450 (CYP) enzymes. When warfarin and PNS were co-administered, the PT and INR increased compared to when warfarin was given alone. 72 hours after administration, compared to the warfarin alone group, the warfarin + low-dose PNS, warfarin + medium-dose PNS, and warfarin + high-dose PNS groups showed 110%, 122%, and 126% increases in PT, respectively (all P < 0.05), as well as 111%, 124%, and 128% increases in INR (all P < 0.05). Compared with the warfarin alone group, the clearance rate (CL/F) of warfarin in the warfarin + low-dose PNS, warfarin + medium-dose PNS, and warfarin + high-dose PNS groups was 10% (P > 0.05), 23% (P < 0.05), and 33% (P < 0.05) lower, respectively, while the systemic exposure (area under the concentration-time curve,AUC0-t) increased by 106% (P > 0.05), 119% (P < 0.05), and 134% (P < 0.05), respectively, and the blood concentration of warfarin incresed by 112%, 113%, and 114%, respectively (all P > 0.05). After combined treatment of HepG2 cells with warfarin + PNS, CYP1A2 expression was upregulated (P < 0.05) and CYP3A4 was downregulated (P < 0.05) but there was no effect on CYP2C9. In animal experiments, PNS had different effect on the expression of CYP1A2 in different doses. While a low dose of PNS resulted in downregulated CYP1A2 expression (P < 0.05), a medium dose resulted in upregulation (P < 0.05), and CYP1A2 expression was not significantly affected by a high dose of PNS (P > 0.05). Meanwhile, PNS at all doses downregulated the expression of CYP3A4 (P < 0.05) but had no effect on the expression of CYP2C9 (P > 0.05). PNS can increase the blood concentration of warfarin, as well as the exposure time, and it can enhance the anticoagulant effect of warfarin by inhibiting the expression of the liver enzyme CYP3A4.

Profiling of warfarin pharmacokinetics‐associated genetic variants: Black Africans portray unique genetic markers important for an African specific warfarin pharmacogenetics‐dosing algorithm

BackgroundWarfarin dose variability observed in patients is attributed to variation in genes involved in the warfarin metabolic pathway. Genetic variation in CYP2C9 and VKORC1 has been the traditional focus in evaluating warfarin dose variability, with little focus on other genes. ObjectiveWe set out to evaluate 27 single nucleotide polymorphisms (SNPs) in the CYP2C cluster loci and 8 genes (VKORC1, ABCB1, CYP2C9, CYP2C19, CYP2C8, CYP1A2, CYP3A4, and CYP3A5) involved in pharmacokinetics of warfarin. Patients/Methods503 participants were recruited among black Africans and Mixed Ancestry population groups, from South Africa and Zimbabwe, and a blood sample taken for DNA. Clinical parameters were obtained from patient medical records, and these were correlated with genetic variation. ResultsAmong black Africans, the SNPs CYP2C rs12777823G>A, CYP2C9 c.449G>A (*8), CYP2C9 c.1003C>T (*11) and CYP2C8 c.805A>T (*2) were significantly associated with warfarin maintenance dose. Conversely, CYP2C9 c.430C>T (*2), CYP2C8 c.792C>G (*4) and VKORC1 g.‐1639G>A were significantly associated with maintenance dose among the Mixed Ancestry. The presence of CYP2C8*2 and CYP3A5*6 alleles was associated with increased mean warfarin maintenance dose, whereas CYP2C9*8 allele was associated with reduced warfarin maintenance dose. ConclusionAfrican populations present with a diversity of variants that are important in predicting pharmacogenetics‐based warfarin dosing in addition to those reported in CYP2C9 and VKORC1. It is therefore important, to include African populations in pharmacogenomics studies to be able to identify all possible biomarkers that are potential predictors for drug response.

Bidirectional Influences of Cranberry on the Pharmacokinetics and Pharmacodynamics of Warfarin with Mechanism Elucidation.

Cranberry is a dietary supplement popularly used for the prophylaxis of urinary tract infection. Interestingly, cranberry–warfarin interactions in clinical reports have shown bidirectional outcomes. (±) Warfarin, a widely prescribed anticoagulant, but with a narrow therapeutic index, contains equal amounts of S- and R-warfarin, of which S-warfarin is more active. The aim of this study was to investigate the effects of different ingestion times of cranberry on the pharmacokinetics and pharmacodynamics of warfarin. Rats were orally administered (±) warfarin (0.2 mg/kg) with and without cranberry (5.0 g/kg) at 0.5 h prior to the warfarin, and at 10 h after the warfarin. The plasma concentrations of S- and R-warfarin were determined by LC/MS. The results indicate that cranberry ingested at 0.5 h before (±) warfarin significantly decreased the systemic exposures of S-warfarin and R-warfarin. Conversely, when cranberry was ingested at 10 h after (±) warfarin, the elimination of S-warfarin was significantly inhibited, and the anticoagulation effect of (±) warfarin was significantly enhanced. The results of the mechanism studies indicate that cranberry activated the breast cancer resistance protein (BCRP), which mediated the efflux transports of S-warfarin and R-warfarin. Moreover, the metabolites of cranberry inhibited cytochrome P450 (CYP) 2C9, the main metabolizing enzyme for S-warfarin. In conclusion, cranberry affected the pharmacokinetics of (±) warfarin in a bidirectional manner by activating the BCRP by CJ during absorption and inhibiting the BCRP and CYP2C9 by CMs during elimination, depending on the ingestion time of CJ. The combined use of cranberry with warfarin should be avoided.

Frequencies of polymorphisms in genes affecting the pharmacokinetics of warfarin in the Zaporizhzhia region

The aim of the study: to establish the frequencies of polymorphisms in VKORC1, CYP2C9 and CYP4F2 genes among residents of the Zaporizhzhia region. Materials and methods. A total of 150 persons (62 male, 88 female) with a median age of 46 years (26; 58) undergoing preventive examination at the Medical Educational and Scientific Center “University Clinic” of Zaporizhzhia State Medical University (ZSMU). The CYP2C9, CYP4F2, VKORC1 genes polymorphisms in atrial fibrillation patients were determined in the Department of Molecular Genetic Studies of the ZSMU Medical Laboratory Center. Amplification of DNA fragments containing polymorphic regions was performed using multiplex real time polymerase chain reaction with Warfarin Pharmacogenetics kits (LLC NPO DNA Technology) in a CFX-96 thermocycler (BioRad) with a fluorescence detection scheme. Results. It was determined that among Zaporizhzhia region residents, the frequencies of CYP2C9*2 genotypes were: C/C – 77.3 %, C/T – 22.7 %, T/T – 0; CYP2C9*3 genotypes: A/A – 88.7 %, A/C – 10.7 %, C/C – 0.6 %; CYP4F2 genotypes: C/C – 56.0 %, C/T – 35.3 %, T/T – 8.7 %; VKORC1 genotypes: G/G – 38.0 %, G/A – 50.0 %, A/A – 12.0 %. There were no statistically significant differences in the distribution of genotype frequencies between males and females and between different age groups. The frequencies of CYP2C9, CYP4F2, VKORC1 genotypes in different populations were compared. Their variability in different geographic regions was established. Conclusions. CYP4F2 and VKORC1 genes polymorphisms are more common in the Zaporizhzhia region, while the prevalence of CYP2C9*2 and CYP2C9*3 genes polymorphisms is much lower. It is necessary to take into account the prevalence of genes polymorphisms that affect warfarin metabolism for each individual population to select its dose by pharmacogenetic testing.

Evaluation of pharmacokinetics of warfarin from validated pharmacokinetic-pharmacodynamic model.

BackgroundPharmacokinetics of warfarin has not been described in our population. We derived the pharmacokinetic parameters from a validated pharmacokinetic-pharmacodynamic model.MethodsPatients receiving warfarin for at least 6 months were recruited and their demographic characteristics, prothrombin time international normalized ratio (PT-INR), warfarin doses and concomitant drugs were collected. Using a validated pharmacokinetic-pharmacodynamic model, we predicted maximum plasma concentration (Cmax), total clearance (CL), volume of distribution (Vd) and elimination rate (k). Warfarin sensitive index (WSI) and warfarin composite measures (WCM) were estimated from the dose and INR values. Liver weight was predicted using validated formula.ResultsTwo-hundred and twenty patients were recruited. The following were the predicted pharmacokinetic parameters: Cmax (mg/L) was 5.8 (0.4); k (L/day) was 1 (0.1); CL (L/day) was 2.1 (0.2); and Vd (L) was 7.6 (0.2). Patients with Cmax and elimination rate outside the mean+1.96 SD had significantly lower WSI and higher WCM. Significant correlations were observed between Cmax with CL, Vd, and k of warfarin. Significant correlations were also observed between CL and Vd of warfarin with liver weight of the study participants.ConclusionWe predicted pharmacokinetic parameters of warfarin from the validated pharmacokinetic-pharmacodynamic model in our population. More studies are needed exploring the relationship between various pharmacodynamic indices of warfarin and pharmacokinetic parameters of warfarin.

Effect of ceritinib on the pharmacokinetics of coadministered CYP3A and 2C9 substrates: a phase I, multicenter, drug\u2013drug interaction study in patients with ALK\u2009+\u2009advanced tumors

PurposeCeritinib is an ALK receptor tyrosine kinase inhibitor approved as first- and second-line treatment in adult patients with ALK + metastatic non-small cell lung cancer (NSCLC). The study investigated the drug–drug interaction (DDI) potential of ceritinib when coadministered with midazolam and warfarin as probe substrates for CYP3A and CYP2C9 activity, respectively.MethodsThis was a phase I, multicenter, open-label, single sequence, crossover DDI study in 33 adult patients with ALK + NSCLC or other advanced tumors. A single dose of a cocktail consisting of midazolam and warfarin was administered with and without concomitant administration of ceritinib. The primary objective was to evaluate the pharmacokinetics of midazolam and warfarin. Secondary objectives included pharmacokinetics, safety, tolerability, overall response rate (ORR), and duration of response (DOR) of ceritinib 750 mg once daily.ResultsCeritinib inhibited CYP3A-mediated metabolism of midazolam, resulting in a markedly increased AUC (geometric mean ratio [90% confidence interval]) by 5.4-fold (4.6, 6.3). Ceritinib also led to an increase in the AUC of S-warfarin by 54% (36%, 75%). The pharmacokinetics and safety profile of ceritinib in this study are consistent with previous reports and no new safety signals were reported. Among the 19 patients with NSCLC, efficacy (ORR: 42.1% and DCR: 63.2%) was similar to that reported previously in studies of pretreated patients with ALK + NSCLC.ConclusionCeritinib is a strong CYP3A inhibitor and a weak CYP2C9 inhibitor. These findings should be reflected as actionable clinical recommendations in the prescribing information for ceritinib with regards to concomitant medications whose pharmacokinetics may be altered by ceritinib.