Lack of the effect of lobeglitazone, a peroxisome proliferator-activated receptor-? agonist, on the pharmacokinetics and pharmacodynamics of warfarin.
ABSTRACT: Lobeglitazone has been developed for the treatment of type 2 diabetes mellitus. This study was conducted to evaluate potential drug-drug interactions between lobeglitazone and warfarin, an anticoagulant with a narrow therapeutic index.In this open-label, three-treatment, crossover study, 24 healthy male subjects were administered lobeglitazone (0.5 mg) for 1-12 days with warfarin (25 mg) on day 5 in one period. After a washout interval, subjects were administered warfarin (25 mg) alone in the other period. Pharmacokinetics of R- and S-warfarin and lobeglitazone, as well as pharmacodynamics of warfarin, as measured by international normalized ratio (INR) and factor VII activity, were assessed.The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for area under the curve from time zero to the time of the last quantifiable concentration (AUClast) for warfarin + lobeglitazone: warfarin alone were 1.0076 (90% CI: 0.9771, 1.0391) for R-warfarin and 0.9880 (90% CI: 0.9537, 1.0235) for S-warfarin. The maximum observed plasma concentration (C max) values were 1.0167 (90% CI: 0.9507, 1.0872) for R-warfarin and 1.0028 (90% CI: 0.9518, 1.0992) for S-warfarin, both of which were contained in the interval 0.80-1.25. Lobeglitazone had no effect on the area under the effect-time curve from time 0 to 168 hours (AUEC) of INR and factor VII activity, as demonstrated by the GMRs of 1.0091 (90% CI: 0.9872, 1.0314) and 0.9355 (90% CI: 0.9028, 0.9695), respectively. In addition, the pharmacokinetics of lobeglitazone was also unaffected by warfarin.Concomitant administration of lobeglitazone and warfarin was well tolerated. Lobeglitazone had no meaningful effect on the pharmacokinetics or pharmacodynamics of warfarin. These findings indicate that lobeglitazone and warfarin can be coadministered without dosage adjustments for either drug.
Project description:BACKGROUND:The application of pharmacogenetic results requires demonstrable correlations between a test result and an indicated specific course of action. We developed a computational decision-support tool that combines patient-specific genotype and phenotype information to provide strategic dosage guidance. This tool, through estimating quantitative and temporal parameters associated with the metabolism- and concentration-dependent response to warfarin, provides the necessary patient-specific context for interpreting international normalized ratio (INR) measurements. METHODS:We analyzed clinical information, plasma S-warfarin concentration, and CYP2C9 (cytochrome P450, family 2, subfamily C, polypeptide 9) and VKORC1 (vitamin K epoxide reductase complex, subunit 1) genotypes for 137 patients with stable INRs. Plasma S-warfarin concentrations were evaluated by VKORC1 genotype (-1639G>A). The steady-state plasma S-warfarin concentration was calculated with CYP2C9 genotype-based clearance rates and compared with actual measurements. RESULTS:The plasma S-warfarin concentration required to yield the target INR response is significantly (P < 0.05) associated with VKORC1 -1639G>A genotype (GG, 0.68 mg/L; AG, 0.48 mg/L; AA, 0.27 mg/L). Modeling of the plasma S-warfarin concentration according to CYP2C9 genotype predicted 58% of the variation in measured S-warfarin concentration: Measured [S-warfarin] = 0.67(Estimated [S-warfarin]) + 0.16 mg/L. CONCLUSIONS:The target interval of plasma S-warfarin concentration required to yield a therapeutic INR can be predicted from the VKORC1 genotype (pharmacodynamics), and the progressive changes in S-warfarin concentration after repeated daily dosing can be predicted from the CYP2C9 genotype (pharmacokinetics). Combining the application of multivariate equations for estimating the maintenance dose with genotype-guided pharmacokinetics/pharmacodynamics modeling provides a powerful tool for maximizing the value of CYP2C9 and VKORC1 test results for ongoing application to patient care.
Project description:To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of edoxaban, an oral direct factor Xa inhibitor, in healthy subjects switching from warfarin.Seventy-two subjects were randomized to edoxaban 60?mg once daily (n = 48) or matching placebo (n = 24) for 5?days at 24?h after the last dose of warfarin treatment (INR 2.0 to 3.0). Safety/tolerability was the primary outcome measure. Pharmacokinetics, INR, aPTT, anti-FXa, thrombin generation and other coagulation assays were assessed.Seventy-two subjects were randomized and 64 subjects received at least one dose of edoxaban (n = 43) or placebo (n = 21) after achieving a target INR of 2.0 to 3.0 on warfarin treatment. Edoxaban 60?mg administered 24?h post-warfarin appeared to be safe and well tolerated. Adverse events were similar across treatments. For bleeding-related adverse events, eight subjects tested positive for faecal occult blood, five subjects during warfarin treatment and three subjects during edoxaban treatment. The mean (SD) baseline (post-dose of warfarin) INR was 2.31 (0.193) which increased to 3.84 (0.744) over 2?h during the edoxaban treatment (P < 0.0001 vs. placebo), returning to post-warfarin baseline within 12?h. A similar time course of effects for the other coagulation assays was observed in accordance with the drugs' mechanisms of action.In this study of healthy subjects, edoxaban administered 24?h after the last dose of warfarin was safe and well tolerated with transient increases across the various coagulation assays above post-warfarin baseline levels.
Project description:Warfarin dosing methods based on existing models for warfarin and the international normalised ratio (INR) give biased maintenance dose predictions at the upper and lower quantiles of dose requirements. The aim of this work is to propose a conceptually different approach to predict INR after warfarin dosing. Factor VII concentration was proposed as the principal driving force for the INR. The time to steady-state INR (tSS,INR) was determined based on the INR response to changes in factor VII concentrations following warfarin initiation, and from this the steady-state INR (INRSS) was derived. The proposed method requires timed, paired blood samples of INR and factor VII. At different simulated warfarin dose rates, the prediction error associated with the proposed method was shown to be within clinically acceptable limits for both the tSS,INR (±2 days) and INRSS (±0.2). The use of the method was demonstrated in two patients who were initiated with 5?mg of warfarin daily. The difference in predicted versus actual steady-state INR were 0.0 and -0.4. The proposed method represents a unique approach to predict the INR. It considers factor VII as the main driver for INR and provides valuable information about the time to steady state INR.
Project description:AIMS: This study investigated relevant pharmacodynamic and pharmacokinetic parameters during the transition from warfarin to rivaroxaban in healthy male subjects. METHODS: Ninety-six healthy men were randomized into the following three groups: warfarin [international normalized ratio (INR) 2.0-3.0] transitioned to rivaroxaban 20?mg once daily (od; group A); warfarin (INR 2.0-3.0) followed by placebo od (group B); and rivaroxaban alone 20?mg od (group C) for 4 days. Anti-factor Xa activity, inhibition of factor Xa activity, prothrombin time (PT), activated partial thromboplastin time, HepTest, prothrombinase-induced clotting time, factor VIIa activity, factor IIa activity, endogenous thrombin potential and pharmacokinetics were measured. RESULTS: An additive effect was observed on the PT and PT/INR during the initial transition period. The mean maximal prolongation of PT was 4.39-fold [coefficient of variation (CV) 18.03%; range 3.39-6.50] of the baseline value in group?A, compared with 1.88-fold (CV 10.35%; range 1.53-2.21) in group?B and 1.57-fold (CV 9.98%; range 1.37-2.09) in group?C. Rivaroxaban had minimal influence on the PT/INR at trough levels. Inhibition of factor Xa activity, activated partial thromboplastin time and endogenous thrombin potential were also enhanced, but to a lesser extent. In contrast, the effects of rivaroxaban on anti-factor Xa activity, HepTest and prothrombinase-induced clotting time were not affected by pretreatment with warfarin. CONCLUSIONS: Changes in pharmacodynamics during the transition from warfarin to rivaroxaban vary depending on the test used. A supra-additive effect on PT/INR is expected during the initial period of transition, but pretreatment with warfarin does not influence the effect of rivaroxaban on anti-factor Xa activity.
Project description:AIMS:Warfarin dose requirement varies significantly. We compared the clinically established doses based on international normalized ratio (INR) among patients with severe thrombosis and/or thrombophilia with estimates from genetic dosing algorithms. METHODS:Fifty patients with severe thrombosis and/or thrombophilia requiring permanent anticoagulation, referred to the Helsinki University Hospital Coagulation Center, were screened for thrombophilias and genotyped for CYP2C9*2 (c.430C>T, rs1799853), CYP2C9*3 (c.1075A>C, rs1057910) and VKORC1 c.-1639G>A (rs9923231) variants. The warfarin maintenance doses (target INR 2.0-3.0 in 94%, 2.5-3.5 in 6%) were estimated by the Gage and the International Warfarin Pharmacogenetics Consortium (IWPC) algorithms. The individual warfarin maintenance dose was tailored, supplementing estimates with comprehensive clinical evaluation and INR data. RESULTS:Mean patient age was 47 years (range 20-76), and BMI 27 (SD 6), 68% being women. Forty-six (92%) had previous venous or arterial thrombosis, and 26 (52%) had a thrombophilia, with 22% having concurrent aspirin. A total of 40% carried the CYP2C9*2 or *3 allele and 54% carried the VKORC1-1639A allele. The daily mean maintenance dose of warfarin estimated by the Gage algorithm was 5.4 mg (95% CI 4.9-5.9 mg), and by the IWPC algorithm was 5.2 mg (95% CI 4.7-5.7 mg). The daily warfarin maintenance dose after clinical visits and follow-up was higher than the estimates, mean 6.9 mg (95% CI 5.6-8.2 mg, P < 0.006), with highest dose in patients having multiple thrombophilic factors (P < 0.03). CONCLUSIONS:In severe thrombosis and/or thrombophilia, variation in thrombin generation and pharmacodynamics influences warfarin response. Pharmacogenetic dosing algorithms seem to underestimate dose requirement.
Project description:Warfarin is a frequently prescribed oral anticoagulant with a narrow therapeutic index, requiring careful dosing and monitoring. However, patients respond with significant inter-individual variability in terms of the dose and responsiveness of warfarin, attributed to genetic polymorphisms within the genes responsible for the pharmacokinetics and pharmacodynamics of warfarin. Extensive warfarin pharmacogenetic studies have been conducted, including studies resulting in genotype-guided dosing guidelines, but few large scale studies have been conducted with the Saudi population. In this study, we report the study design and baseline characteristics of the Saudi WArfarin Pharmacogenomics (SWAP) cohort, as well as the association of the VKORC1 promoter variants with the warfarin dose and the time to a stable INR. In the 936 Saudi patients recruited in the SWAP study, the minor allele C of rs9923231 was significantly associated with a 8.45 mg higher weekly warfarin dose (p value?=?4.0?×?10-46), as well as with a significant delay in achieving a stable INR level. The addition of the rs9923231 status to the model, containing all the significant clinical variables, doubled the warfarin dose explained variance to 31%. The SWAP cohort represents a valuable resource for future research with the objective of identifying rare and prevalent genetic variants, which can be incorporated in personalized anticoagulation therapy for the Saudi population.
Project description:The primary objective was to explore the pharmacodynamic changes during transition from rivaroxaban to warfarin in healthy subjects. Safety, tolerability and pharmacokinetics were assessed as secondary objectives.An open label, non-randomized, sequential two period study. In treatment period 1 (TP1), subjects received rivaroxaban 20 mg once daily (5 days), followed by co-administration with a warfarin loading dose regimen of 5 or 10 mg (for the 10 mg regimen, the dose could be uptitrated to attain target international normalized ratio [INR] ≥2.0) once daily (2-4 days). When trough INR values ≥2.0 were attained, rivaroxaban was discontinued and warfarin treatment continued as monotherapy (INR 2.0-3.0). During treatment period 2, subjects received the same warfarin regimen as in TP1, but without rivaroxaban.During co-administration, maximum INR and prothrombin time (PT) values were higher than with rivaroxaban or warfarin monotherapy. The mean maximum effect (Emax ) for INR after co-administration was 2.79-4.15 (mean PT Emax 41.0-62.7 s), compared with 1.41-1.74 (mean PT Emax 20.1-25.2 s) for warfarin alone. However, rivaroxaban had the smallest effect on INR at trough rivaroxaban concentrations. Neither rivaroxaban nor warfarin significantly affected maximum plasma concentrations of the other drug.The combined pharmacodynamic effects during co-administration of rivaroxaban and warfarin were greater than additive, but the pharmacokinetics of both drugs were unaffected. Co-administration was well tolerated. When transitioning from rivaroxaban to warfarin, INR monitoring during co-administration should be performed at the trough rivaroxaban concentration to minimize the effect of rivaroxaban on INR.
Project description:AIM:The aim of the present study was to evaluate the effect of the proposed organic cation transporter (OCT) inhibitor daclatasvir on the pharmacokinetics and pharmacodynamics of the OCT substrate metformin. METHODS:This was an open-label, two-period, randomized, crossover trial in 20 healthy subjects. Treatment A consisted of metformin and treatment B consisted of metformin + daclatasvir. Pharmacokinetic curves were recorded at steady-state. Geometric mean ratios (GMRs) with 90% confidence intervals (CIs) were calculated for metformin area under the concentration-time curve from 0 h to 12 h (AUC0-12 ), maximum plasma concentration (Cmax ) and final plasma concentration (Clast ). An oral glucose tolerance test was performed, measuring insulin, glucose and lactate levels. RESULTS:The GMRs (90% CI) of metformin AUC0-12 , Cmax and Clast (B vs. A) were 109% (102-116%), 108% (101-116%) and 112% (103-122%). The geometric mean AUC0-2 for insulin, glucose and lactate during treatments A and B were 84 h. mEl-1 and 90 h. mEl-1 , 13.6 h. mmol l-1 and 13.4 h. mmol l-1 , and 3.4 h. mmol l-1 and 3.5 h. mmol l-1 , respectively. CONCLUSIONS:Bioequivalence analysis showed that daclatasvir does not influence the pharmacokinetics of metformin in healthy subjects. Pharmacodynamic parameters were also comparable between treatments.
Project description:AIMS:The aims of this study are to apply a theory-based mechanistic model to describe the pharmacokinetics (PK) and pharmacodynamics (PD) of S- and R-warfarin. METHODS:Clinical data were obtained from 264 patients. Total concentrations for S- and R-warfarin were measured by ultra-high performance liquid tandem mass spectrometry. Genotypes were measured using pyrosequencing. A sequential population PK parameter with data method was used to describe the international normalized ratio (INR) time course. Data were analyzed with NONMEM. Model evaluation was based on parameter plausibility and prediction-corrected visual predictive checks. RESULTS:Warfarin PK was described using a one-compartment model. CYP2C9 *1/*3 genotype had reduced clearance for S-warfarin, but increased clearance for R-warfarin. The in vitro parameters for the relationship between prothrombin complex activity (PCA) and INR were markedly different (A = 0.560, B = 0.386) from the theory-based values (A = 1, B = 0). There was a small difference between healthy subjects and patients. A sigmoid Emax PD model inhibiting PCA synthesis as a function of S-warfarin concentration predicted INR. Small R-warfarin effects was described by competitive antagonism of S-warfarin inhibition. Patients with VKORC1 AA and CYP4F2 CC or CT genotypes had lower C50 for S-warfarin. CONCLUSION:A theory-based PKPD model describes warfarin concentrations and clinical response. Expected PK and PD genotype effects were confirmed. The role of predicted fat free mass with theory-based allometric scaling of PK parameters was identified. R-warfarin had a minor effect compared with S-warfarin on PCA synthesis. INR is predictable from 1/PCA in vivo.
Project description:BACKGROUND: To determine the contribution of cytochrome P4502C9 (CYP2C9), vitamin K epoxide reductase (VKORC1) and factor VII genotypes, age, body mass index (BMI), international normalized ratio (INR) and other individual patient characteristics on warfarin dose requirements in an adult Turkish population. METHODS: Blood samples were collected from 101 Turkish patients. Genetic analyses for CYP2C9*2 and *3, VKORC1 -1639 G>A and factor VII -401 G>T polymorphisms were performed. Age, INR, BMI values and other individual patient characteristics were also recorded. RESULTS: The mean daily warfarin dosage was significantly higher in patients with the CYP2C9*1/*1 genotype than in the CYP2C9*2/*2 and CYP2C9*1/*3 groups (p ≤ 0.05). With respect to the VKORC1 -1639 G>A polymorphism, the mean warfarin daily dose requirement was higher in the wild type group compared to the heterozygous group (p≤0.001). The mean daily dose requirement for patients with the GG form of factor VII was significantly higher than that of patients with the TT genotype (p ≤ 0.05). Age, gender, BMI, INR had no statistically significant correlation with warfarin dose (p ≥ 0.05). CONCLUSIONS: Polymorphisms in CYP2C9, VKORC1 and factor VII did partially affect daily warfarin dose requirements, while age, gender, BMI and INR do not. However, further case-control studies with a larger study size and different genetic loci are needed to confirm our study.