Edoxaban Versus Warfarin in Patients With Atrial Fibrillation and History of Liver Disease.

BACKGROUND: Patients with liver disease have increased risk of thrombosis and bleeding but are typically excluded from trials of direct oral anticoagulant agents. OBJECTIVES: This study evaluated the pharmacokinetics (PK), pharmacodynamics (PD), clinical efficacy and safety of edoxaban versus warfarin in patients with atrial fibrillation (AF) and history of liver disease. METHODS: ENGAGE AF-TIMI 48 (Effective Anticoagulation With Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis In Myocardial Infarction Study 48) was a randomized, double-blind trial comparing edoxaban with warfarin in patients with AF followed for 2.8 years. History of liver disease was defined as investigator-reported liver disease or >2-fold transaminase elevation at randomization. The primary efficacy and safety endpoints of stroke or systemic embolic event (SSEE) and major bleeding were assessed stratified by history of liver disease. PK/PD assessments of edoxaban included endogenous and extrinsic factor Xa activity and edoxaban concentration. RESULTS: Among 21,105 patients, 1,083 (5.1%) had a history of liver disease; they had a higher prevalence of many comorbidities. The adjusted risks of SSEE were similar (adjusted hazard ratio [HRadj]: 0.90; 95% confidence interval [CI]: 0.67 to 1.22; p = 0.50), but major bleeding was more common in patients with liver disease (HRadj: 1.38; 95% CI: 1.10 to 1.74; p = 0.005). There were no significant differences in PK/PD assessment of edoxaban in patients with versus without liver disease. The HRs for higher-dose edoxaban versus warfarin for SSEE were 0.86 (95% CI: 0.73 to 1.01) in patients without and 1.11 (95% CI: 0.54 to 2.30) with liver disease (p for interaction [pint] = 0.47), major bleeding 0.80 (95% CI: 0.70 to 0.91) in patients without and 0.91 (95% CI: 0.56 to 1.47) with liver disease (pint = 0.63). There were no significant differences in hepatic adverse events between the 2 treatment groups. CONCLUSIONS: Among patients with AF receiving oral anticoagulation, bleeding, but not thromboembolic events, was increased in patients with liver disease. A history of liver disease did not alter the relative efficacy and safety of edoxaban compared with warfarin. Hepatic adverse events were similar between edoxaban and warfarin.

Linking Endogenous Factor Xa Activity, a Biologically Relevant Pharmacodynamic Marker, to Edoxaban Plasma Concentrations and Clinical Outcomes in the ENGAGE AF-TIMI 48 Trial.

BACKGROUND: We previously reported exogenous antifactor Xa (FXa) activity as a pharmacokinetic surrogate marker for edoxaban plasma concentrations. Inhibition of endogenous FXa activity is a more biologically relevant pharmacodynamic measure of edoxaban activity. Here we describe the value of endogenous FXa activity as a pharmacodynamic marker linking edoxaban concentrations and clinical outcomes in the ENGAGE AF-TIMI 48 trial (Effective Anticoagulation With Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis in Myocardial Infarction Study 48). METHODS: In ENGAGE AF-TIMI 48, edoxaban was administered in higher dose (60/30 mg QD) and lower dose (30/15 mg QD) regimens. Both regimens incorporated a 50% dose reduction in patients with characteristics known to increase edoxaban concentration. Pharmacokinetic-pharmacodynamic modeling was performed in a subgroup of 3029 patients who had samples collected for endogenous FXa activity (measured using an assay after endogenous FX was activated with Russell viper venom). RESULTS: Endogenous FXa activity decreased with increasing edoxaban concentrations of ≤440 ng/mL, indicating that inhibition of endogenous FXa activity is saturated above this concentration threshold. Baseline endogenous FXa activity averaged 92.1±20.9% (relative to normal control samples) and was lower with older age, with lower body weight, and in male patients. Model-predicted 24-hour average percentages of inhibition of endogenous FXa activity were 35.8±5.18, 29.1±3.92, 21.9±3.80, and 16.4±2.70 for the higher dose edoxaban regimen 60 mg, dose-reduced higher dose edoxaban regimen 30 mg, lower dose edoxaban regimen 30 mg, and dose-reduced lower dose edoxaban regimen 15 mg groups, respectively. A greater average percentage of inhibition of endogenous FXa activity was associated with a lower incidence of ischemic stroke or systemic embolism and a higher risk of major bleeding ( P<0.001). In a typical subject, the predicted risks for the 10th and 90th percentiles of inhibition of endogenous FXa activity were 1.04% and 0.57% for incidence of ischemic stroke or systemic embolism and 1.35% and 2.33% for major bleeding, respectively. CONCLUSIONS: The extent of inhibition of endogenous FXa activity is influenced by edoxaban dosing and clinical characteristics, and it is associated with both antithrombotic benefit and risk of bleeding. This approach of linking endogenous FXa activity to clinical outcomes may be used to guide dose selection in future clinical trials, monitor patients in certain clinical scenarios, or refine the doses of oral FXa inhibitors in patients who require precise anticoagulation therapy. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT00781391.

Uninterrupted administration of edoxaban vs vitamin K antagonists in patients undergoing atrial fibrillation catheter ablation: Rationale and design of the ELIMINATE-AF study.

Patients with atrial fibrillation (AF) are at an approximately 0.5% to 3% increased risk of thromboembolism during and immediately after catheter ablation. Treatment guidelines recommend periprocedural oral anticoagulation plus unfractionated heparin during ablation. Rivaroxaban and dabigatran are the only non-vitamin K oral anticoagulants for which there are randomized controlled trials assessing uninterrupted anticoagulation in patients undergoing catheter ablation of AF. Edoxaban, a direct factor Xa inhibitor, is noninferior vs warfarin for the prevention of stroke or systemic embolism with less major bleeding in patients with nonvalvular AF. The ELIMINATE-AF (Evaluation of Edoxaban Compared With VKA in Subjects Undergoing Catheter Ablation of Nonvalvular Atrial Fibrillation) trial is a multinational, multicenter, prospective, randomized, open-label, parallel-group, blinded-endpoint evaluation (PROBE) study to assess the safety and efficacy of once-daily edoxaban 60 mg (30 mg in patients indicated for a dose reduction) vs vitamin K antagonists (VKA) in patients with nonvalvular AF undergoing catheter ablation (http://www.ClinicalTrials.gov: NCT02942576). A total of 560 patients are planned for randomization to edoxaban or VKA (2:1 ratio) to obtain 450 patients fully compliant with the protocol. Patients will complete 21 to 28 days of anticoagulation prior to the ablation and a 90-day post-ablation period. The primary efficacy endpoint is the composite of all-cause death, stroke, and major bleeding. The primary safety endpoint is major bleeding. A magnetic resonance imaging substudy will assess the incidence of silent cerebral lesions post-ablation. ELIMINATE-AF will define the efficacy and safety of edoxaban for uninterrupted oral anticoagulation during catheter ablation of AF.

Population pharmacokinetic modeling and simulation for assessing renal impairment effect on the pharmacokinetics of mirogabalin.

A population pharmacokinetic model was developed to describe plasma concentrations of mirogabalin and lactam metabolite, obtained following a single oral dose of 5 mg mirogabalin to subjects with varying degrees of renal function.A 2-compartment model was used for both mirogabalin and lactam metabolite. Body weight was a significant covariate on volume of distribution of mirogabalin and lactam metabolite, whereas creatinine clearance significantly affected both renal and nonrenal clearance of mirogabalin. The total clearance of mirogabalin was decreased by 25%, 54%, and 76% in subjects with mild, moderate, and severe renal impairment, respectively, relative to normal controls. Simulation results showed that in comparison with the normal renal function group receiving mirogabalin 15 mg once or twice daily, dose reduction by 50% or 75% in subjects with moderate or severe renal impairment would produce similar AUCss values, but 37%-43% or 28%-32% lower Cmax,ss of mirogabalin. Predicted mirogabalin AUCss was 26% higher, whereas Cmax,ss was similar in subjects with mild renal impairment compared with those having normal renal function taking the same dose. Results support a dose reduction by 50% or 75% in subjects with moderate or severe renal impairment. No dose adjustment seemed necessary for subjects with mild renal impairment.

Evaluating a physiologically based pharmacokinetic model for prediction of omeprazole clearance and assessing ethnic sensitivity in CYP2C19 metabolic pathway.

PURPOSE: The purpose of this study is to evaluate the ethnicity-specific population models in the SimCYP Simulator® for prediction of omeprazole clearance with attention to differences in the CYP2C19 metabolic pathway. METHODS: The SimCYP® models incorporating Caucasian, Chinese, and Japanese population-specific demographic, physiological, and enzyme data were applied to simulate omeprazole pharmacokinetics. Published pharmacokinetic data of omeprazole after intravenous or oral administration in Caucasian, Chinese, and Japanese were used for the evaluation. RESULTS: Following oral administration, the ratio of the predicted to observed geometric mean of omeprazole clearance in Caucasian extensive metabolizers (EMs) was 0.88. The ratios in Chinese EMs were 1.16 and 0.99 after intravenous and oral administration, respectively. The ratios in Japanese EMs were 0.88 and 0.71 after intravenous and oral administration, respectively. Significant differences (2-fold) in the observed oral clearance of omeprazole were identified between Caucasian and Asian (Chinese and Japanese) EMs while the observed oral and intravenous clearances of omeprazole were similar between Chinese and Japanese EMs. Physiologically based pharmacokinetics (PBPK) models within SimCYP accurately predicted the difference in the observed oral clearance between Caucasian and Chinese EMs but overpredicted the difference between Caucasians and Japanese EMs due to under-prediction of oral clearance in Japanese EMs. CONCLUSIONS: The PBPK model within SimCYP adequately predicted omeprazole clearance in Caucasian, Chinese, and Japanese EMs and the 2-fold differences in clearance of omeprazole between Caucasian and Asian EMs. This may lead to early identification of ethnic sensitivity in clearance and the need for different dosing regimens in a specific ethnic group for substrates of CYP2C19 which can support the rational design of bridging clinical trials.

Population pharmacokinetics and dose-exposure proportionality of edoxaban in healthy volunteers.

BACKGROUND AND OBJECTIVES: Edoxaban is a novel direct inhibitor of activated factor Xa. A previous human pharmacokinetic study suggested a less than proportional increase in edoxaban exposure at higher dose concentrations, but the quantitative relationship, including the point of inflection, has not yet been fully characterized. The objectives of this analysis were to characterize the population pharmacokinetics and quantify the dose-exposure relationship of edoxaban over a dose range of 10-180 mg. METHODS: Concentration data from 278 subjects in five phase I clinical studies were used to perform a population pharmacokinetic analysis using non-linear mixed-effects modeling. Model performance was assessed by standard goodness-of-fit diagnostic plots, visual predictive check, and bootstrapping procedures. RESULTS: Edoxaban pharmacokinetics were described by a two-compartment model, with first-order absorption preceded by a lag time for absorption (t lag). Edoxaban relative bioavailability (F 1) was estimated as 67.2 % and remained constant at the dose range of 10-30 mg. For doses above 30 mg, every 30-mg dose increase was associated with an approximately 6.7 % decrease in F 1. Sex was identified as a significant covariate on clearance (CL), with female subjects showing 13.1 % lower CL than male subjects. Food was found to affect t lag, but not F 1. When compared with the fasted state, administration of edoxaban with food prolonged t lag from 0.233 to 0.375 h. CONCLUSIONS: The population pharmacokinetic model provided an adequate description of the observed data. The analysis results suggested a less than proportional dose-exposure relationship for edoxaban at a dose above 30 mg. A statistically significant sex effect on CL and food effect on t lag were identified but are unlikely to be clinically important.

Edoxaban population pharmacokinetics and exposure-response analysis in patients with non-valvular atrial fibrillation.

PURPOSE: The aim of this study was to evaluate the population pharmacokinetics (PK) and exposure-response relationship of edoxaban in patients with non-valvular atrial fibrillation (AF). METHODS: Concentration data from 1,134 subjects in 11 clinical studies (eight phase I, one phase II, and two phase III) were used to perform a population PK analysis, including estimation of the bioavailability and quantification of the effects of P-glycoprotein (P-gp) inhibitors as well as renal impairment on edoxaban PK. The potential relationship between edoxaban PK exposure and incidence of bleeding events was explored based on data from 893 AF patients. RESULTS: Absolute bioavailability of edoxaban was estimated as 58.3 %. With oral dosing of edoxaban, co-administration of various P-gp inhibitors significantly increased edoxaban bioavailability and decreased volume of distribution (V 2), resulting in a predicted increase of 33-77 % in area under the curve (AUC) and 65-104 % in C max. A much smaller increase was seen in edoxaban concentration at 24 h post-dose (C 24, -24 to 38 %), due to decreased V 2 and shortened elimination half-life. With IV dosing of edoxaban, co-administration of the P-gp inhibitor quinidine decreased both edoxaban clearance (CL) and V 2, resulting in an increase of 32 % in AUC and 66 % in C 24. Creatinine clearance was a significant covariate on renal clearance, whereas age and body weight significantly affected nonrenal clearance. Model-predicted steady state C min was slightly higher, but AUC was comparable for patients who had severe renal impairment and received edoxaban 15 mg once daily (QD) versus patients who had normal renal function or mild renal impairment and received edoxaban 30 mg QD. Exposure-response analysis suggested that edoxaban C min and country/region are significantly associated with the incidence of bleeds. CONCLUSIONS: The model provided reasonable estimation with regard to the absolute bioavailability of edoxaban, the magnitude of change in edoxaban exposure upon co-administration of P-gp inhibitors, and the impact of renal impairment on edoxaban clearance. Analysis results supported a 50 % dose reduction scheme for subjects with severe renal impairment. Further confirmation will be sought by incorporating clinical safety and efficacy information from larger phase III trials.

Nilotinib population pharmacokinetics and exposure-response analysis in patients with imatinib-resistant or -intolerant chronic myeloid leukemia.

PURPOSE: We evaluated the population pharmacokinetics (PK) and exposure-response relationship of nilotinib in patients with imatinib-resistant or -intolerant chronic myeloid leukemia (CML). METHODS: Concentration data from 493 patients with CML in chronic phase (CML-CP), accelerated phase, or blast crisis were used to perform a population pharmacokinetic analysis using nonlinear mixed-effect modeling. Steady-state nilotinib trough concentrations (Cmin) in individual patients were estimated from the population PK model for correlation with the efficacy and safety variables. Exposure-efficacy analysis was performed in patients with CML-CP, whereas exposure-safety analysis was performed in all patients who had both nilotinib PK data and efficacy/safety measures available. RESULTS: Baseline demographics and CML disease phase did not significantly affect nilotinib PK. Patients with a lower Cmin had significantly longer time to complete cytogenetic response (P = 0.010), longer time to major molecular response (P = 0.012), shorter time to progression (TTP; P = 0.009), and a trend toward lower response rates vs. patients with higher Cmin. A joint effect of prognostic risk score and Cmin on TTP was significant (P < 0.001). Nilotinib Cmin was also associated with the occurrence of all-grade elevations in total bilirubin (P < 0.001) and lipase (P = 0.002) levels. CONCLUSIONS: When tolerability allows, adherence to the nilotinib dose (400 mg twice daily) in order to maintain sufficient Cmin is important in maximizing the efficacy of nilotinib in patients with imatinib-resistant or -intolerant CML.

Effects of famotidine or an antacid preparation on the pharmacokinetics of nilotinib in healthy volunteers.

PURPOSE: This study evaluated the effects of either famotidine or antacid on the pharmacokinetics of nilotinib in healthy subjects, with the specific focus to explore different dosing separation schemes leading to a minimized drug-drug interaction. METHODS: Fifty-two subjects were randomized to receive the following treatments in a crossover manner: (A) single oral nilotinib 400 mg alone; (B) famotidine 20 mg twice a day for 3 days, followed by a single administration of nilotinib 400 mg and famotidine 20 mg on Day 4, where famotidine was given 2 h after nilotinib; (C) single oral nilotinib 400 mg and antacid suspension 20 mL, where antacid was given 2 h before nilotinib; (D) single oral nilotinib 400 mg and antacid suspension 20 mL, where antacid was given 2 h after nilotinib. RESULTS: Comparing Treatment B to Treatment A, the geometric mean ratios of nilotinib C(max), AUC(0-tlast), and AUC(0-inf) were 0.966, 0.984, and 0.911, respectively (90% confidence intervals (CIs), 0.875-1.066, 0.905-1.069, and 0.798-1.039, respectively). Nilotinib pharmacokinetic parameters following Treatment C or Treatment D were similar to those after Treatment A; the corresponding 90% CIs of the geometric mean ratios of C(max), AUC(0-tlast), and AUC(0-inf) all fell within the bioequivalence range of 0.8-1.25. CONCLUSIONS: Neither famotidine nor antacid significantly affected nilotinib pharmacokinetics. When concurrent use of an H2 blocker or an antacid is necessary, the H2 blocker may be administered 10 h before and 2 h after nilotinib dose, or the antacid may be administered 2 h before or 2 h after nilotinib dose.

Effects of CYP2D6*10, CYP3A5*3, CYP1A2*1F, and ABCB1 C3435T polymorphisms on the pharmacokinetics of flecainide in healthy Chinese subjects.

BACKGROUND: Although flecainide is thought to be meta-bolized predominantly by cytochrome P450 (CYP) 2D6, it shows pharmacokinetic interactions with drugs, such as verapamil and digoxin, which may suggest other CYP pathways or ATP-binding cassette (ABC) transporters might be involved. This study evaluated effects of common polymorphisms in Chinese in CYP2D6, CYP3A5, CYP1A2, and ABCB1 on flecainide pharmacokinetics. METHODS: Single oral 100-mg doses of flecainide were given to 15 healthy male Chinese subjects who were genotyped for the CYP2D6*2, *5, *10, CYP3A5*3, CYP1A2*1F and ABCB1 C1236T, G2677T/A, and C3435T polymorphisms. RESULTS: There was no significant difference in the pharmacokinetics of flecainide among CYP2D6 (mainly involving *10) genotypes. The CYP3A5*3/*3 subjects (n=8) had a 26% higher systemic exposure (AUC0-∞) and 17% lower apparent oral clearance of flecainide than the combined group of CYP3A5*1/*1 (n=6) and CYP3A5*1/*3 (n=1) subjects (p<0.05). Subjects homozygous for CYP1A2*1F tended to have lower systemic exposure and increased clearance of flecainide compared to those with CYP1A2*1A/1F in subjects with at least one CYP2D6 variant allele. CONCLUSIONS: The disposition of flecainide appeared to be influenced by the CYP3A5*3 and possibly the CYP1A2*1F polymorphisms, particularly in subjects with CYP2D6 variant alleles.

Concurrent use of proton pump inhibitors or H2 blockers did not adversely affect nilotinib efficacy in patients with chronic myeloid leukemia.

PURPOSE: The impact of proton pump inhibitors (PPIs) and histamine H2 receptor antagonists (H2 blockers) on the efficacy of nilotinib was evaluated. METHODS: Retrospective analyses were performed in patients with newly diagnosed Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia in chronic phase (CML-CP; N = 492) and in patients with imatinib-resistant or imatinib-intolerant Ph+ CML-CP (N = 256) treated with nilotinib. RESULTS: In the newly diagnosed population, 87 (17.7 %) and 49 (10.0 %) patients received PPIs and H2 blockers, respectively. Major molecular response at 12 months was achieved by 59 (49.6 %) patients who received at least one PPI or H2 blocker (n = 119) and 153 (41.0 %) patients who did not receive any comedication (n = 373; P = 0.13). PPIs and H2 blockers were used by 77 (30.1 %) and 17 (6.6 %) patients with imatinib-resistant or imatinib-intolerant CML-CP, respectively. Major cytogenetic response by 12 months was achieved by 55 (64.0 %) patients who received at least one PPI or H2 blocker (n = 86) versus 98 (57.6 %) patients who did not receive any comedication (n = 170; P = 0.40); 39 (45.3 %) versus 65 (38.2 %), respectively, achieved complete cytogenetic response by 12 months (P = 0.34). Similar findings were observed in patients who received comedication for >50 % of the time on nilotinib therapy. Nilotinib steady-state trough concentration was not affected by the presence of PPIs or H2 blockers. CONCLUSIONS: Concurrent use of PPIs or H2 blockers did not affect the pharmacokinetics and efficacy of nilotinib in patients with Ph+ CML-CP.

Population pharmacokinetic and exposure-response analysis of nilotinib in patients with newly diagnosed Ph+ chronic myeloid leukemia in chronic phase.

PURPOSE: We investigated the population pharmacokinetics and exposure-response relationship of nilotinib in patients with newly diagnosed chronic myeloid leukemia (CML) in chronic phase. METHODS: Nilotinib was given at 300 mg or 400 mg twice daily. Serum concentration data (sparse and full pharmacokinetic profiles) were obtained from 542 patients over 12 months. A population pharmacokinetic analysis was performed using nonlinear mixed-effect modeling. Exposure-response relationships were explored graphically or using logistic regression models. RESULTS: Nilotinib concentrations were stable over 12 months. Patients in the 400 mg twice-daily arm had an 11.5% higher exposure than did those in the 300 mg twice-daily arm, and the relative bioavailability of nilotinib 400 mg twice daily was 0.84 times that of 300 mg twice daily. Patient demographics did not significantly affect nilotinib pharmacokinetics. The occurrence of all-grade total bilirubin elevation was significantly higher in patients with higher nilotinib exposure, and a positive correlation was also observed between nilotinib exposure and QTcF change on electrocardiograms from baseline. There was no significant relationship between nilotinib exposure and major molecular response at 12 months. CONCLUSIONS: There is a less than proportional dose-exposure relationship between nilotinib 300 mg and 400 mg twice-daily doses. Blood level testing is unlikely to play an important role in the general management of patients with newly diagnosed CML treated with nilotinib.

Omeprazole limited sampling strategies to predict area under the concentration-time curve ratios: implications for cytochrome P450 2C19 and 3A phenotyping.

PURPOSE: To develop a limited sampling strategy (LSS) to predict area under the concentration-time curve (AUC) ratios of omeprazole (AUC(OPZ)) to its metabolites 5-hydroxyomeprazole (AUC(5OH)) and omeprazole sulfone (AUC(SUL)) as phenotyping parameters for cytochrome P450 (CYP) 2C19 and 3A. METHODS: Data were obtained from 37 (4 women) Caucasian, Chinese, and Korean healthy adults from three published studies. The AUC(OPZ), AUC(5OH), and AUC(SUL) were calculated via noncompartmental analysis. Observed AUC(OPZ, OBS)/AUC(5OH, OBS) and AUC(OPZ, OBS)/AUC(SUL, OBS) were determined. Plasma concentrations of omeprazole, 5-hydroxyomeprazole, and omeprazole sulfone at 1, 1.5, 2, 3, 4, 6, and 8 h post-dose were used to generate limited sampling strategy (LSS) models to predict AUC(OPZ,PRE)/AUC(5OH,PRE) and AUC(OPZ,PRE/)AUC(SUL,PRE). Bias and precision were assessed via percentage mean prediction error (%MPE) and percentage mean absolute error (%MAE), with acceptable limits being <15%. RESULTS: For CYP2C19, the AUC(OPZ,OBS)/AUC(5OH,OBS) was [mean ± standard deviation (SD)] 2.10 ± 1.63. Five LSS models of AUC(OPZ,PRE)/AUC(5OH,PRE) were generated, but none met the bias or precision criteria. Upon stratification by CYP2C19 genotype and ethnicity, a three-timepoint (at 1, 2, and 4 h) LSS model accurately predicted AUC(OPZ)/AUC(5OH) in Caucasian CYP2C19*1/*1 subjects. For CYP3A, AUC(OPZ,OBS)/AUC(SUL,OBS) (mean ± SD) was 1.79 ± 0.67. All LSS models had unacceptable %MAE, even when stratified by CYP2C19 genotype and ethnicity. CONCLUSIONS: A LSS model to predict AUC(OPZ)/AUC(5OH), and thus CYP2C19 activity, was generated for Caucasian CYP2C19*1/*1 subjects. However, additional model validation is needed prior to general use. LSS models to predict AUC(OPZ)/AUC(SUL), and thus CYP3A activity, were not possible, even upon stratification by CYP2C19 genotype and ethnicity.

Effects of yogurt and applesauce on the oral bioavailability of nilotinib in healthy volunteers.

Nilotinib, a potent orally bioavailable BCR-ABL tyrosine kinase inhibitor, is currently available as a hard gelatin capsule that must be swallowed whole. For patients who may have difficulty swallowing the intact capsule, an alternative mode of administration is desirable. The authors compared the bioavailability of nilotinib from the following administrations in 48 healthy subjects: (1) 400 mg nilotinib given as two 200-mg nilotinib intact capsules; (2) contents of two 200-mg nilotinib capsules, each capsule dispersed in 1 teaspoon of nonfat plain yogurt; and (3) contents of two 200-mg nilotinib capsules, each capsule dispersed in 1 teaspoon of applesauce. Nilotinib absorption was modestly increased following the administration of nilotinib dispersed in yogurt. The geometric mean ratios (90% confidence intervals) for nilotinib C(max), AUC(0-tlast), and AUC(0-inf) were 1.31 (1.22-1.41), 1.11 (1.05-1.16), and 1.08 (1.02-1.15), respectively. Administration of nilotinib dispersed in applesauce showed equivalent bioavailability compared with administration of nilotinib as intact capsules. The geometric mean ratios (90% confidence intervals) for nilotinib C(max), AUC(0-tlast), and AUC(0-inf) were 0.95 (0.88-1.02), 0.99 (0.94-1.04), and 0.97 (0.90-1.03), respectively. Each treatment was well tolerated in the study subjects. The data support a feasible alternative method of nilotinib administration; each capsule's contents may be dispersed in 1 teaspoon of applesauce and taken immediately.

Effects of rifampin and ketoconazole on the pharmacokinetics of nilotinib in healthy participants.

Nilotinib (Tasigna), an orally bioavailable second-generation BCR-ABL tyrosine kinase inhibitor, is approved for use in patients with chronic myeloid leukemia in chronic phase and accelerated phase who are resistant or intolerant to prior therapy, including imatinib. Previous in vitro studies indicated that nilotinib metabolism is primarily mediated by CYP3A4. To investigate the effect of CYP3A4 induction and inhibition on nilotinib pharmacokinetics, 2 studies were conducted in healthy volunteers prior to and following treatment with a strong inducer (rifampin) or inhibitor (ketoconazole). In the induction study, administration of rifampin 600 mg once daily for 8 days significantly increased urinary 6ß-hydroxycortisol/ cortisol ratio, from a preinduction baseline of 5.8 ± 2.7 to 18.0 ± 10.2 after 8 days of rifampin treatment, confirming an inductive effect on CYP3A4. Nilotinib oral clearance was increased by 4.8-fold, and the maximum serum concentration (C(max)) and area under the serum concentration-time curve (AUC) were decreased by 64% and 80%, respectively, in the induced state compared with baseline. In the inhibition study, ketoconazole 400 mg once daily for 6 days increased the C(max) and AUC of nilotinib by 1.8- and 3-fold, respectively, compared with nilotinib alone. These results indicate that concurrent use of strong CYP3A4 inducers or inhibitors may necessitate dosage adjustments of nilotinib and should be avoided when possible.

Effects of nilotinib on single-dose warfarin pharmacokinetics and pharmacodynamics: a randomized, single-blind, two-period crossover study in healthy subjects.

BACKGROUND AND OBJECTIVE: Nilotinib (Tasigna®), a highly selective and potent BCR-ABL tyrosine kinase inhibitor, is approved for the treatment of chronic myeloid leukaemia in the chronic phase (CML-CP) and the accelerated phase (CML-AP) in patients resistant or intolerant to prior therapy, including imatinib. Nilotinib has shown competitive inhibition of cytochrome P450 enzyme (CYP) 2C9 in vitro, but its effect on CYP2C9 activity in humans is unknown. This study evaluated the effects of nilotinib on the pharmacokinetics and pharmacodynamics of warfarin, a sensitive CYP2C9 substrate, in healthy subjects. METHODS: Twenty-four subjects (six female, 18 male, aged 21-65 years) were enrolled to receive a single oral dose of warfarin 25 mg with either a single oral dose of nilotinib 800 mg or matching placebo (all administered 30 minutes after consumption of a high-fat meal) in a crossover design. Serial blood samples were collected post-dose for determining serum concentrations of nilotinib and plasma concentrations of S- and R-warfarin. Prothrombin time (PT) and international normalized ratio (INR) values were determined as pharmacodynamic measures of warfarin activity. CYP2C9 genotyping was performed in all subjects using TaqMan® assay. RESULTS: Sixteen subjects were identified as CYP2C9 extensive metabolizers (EMs) and eight as intermediate metabolizers (IMs). There were no CYP2C9 poor metabolizers. Pharmacokinetic parameters of S- and R-warfarin were similar between the two treatments (warfarin + nilotinib vs warfarin alone) in both the EM and the IM groups. The geometric mean ratios (90% CIs) for the maximum concentration in plasma (C(max)) and area under the concentration-time curve from time zero to infinity (AUC(∞)) of S-warfarin in plasma in all subjects were 0.98 (0.95, 1.02) and 1.03 (0.99, 1.07), respectively, and for R-warfarin 1.00 (0.96, 1.04) and 1.02 (0.99, 1.04), respectively. Mean ratios for the maximum observed value and AUC from time zero to the last sampling time for PT were 1.00 (0.96, 1.04) and 1.00 (0.98, 1.02), respectively, and for the maximum observed value for INR and the AUC from time zero to the last sampling time for INR were 1.00 (0.97, 1.03) and 1.00 (0.99, 1.01), respectively. Mean ± SD serum nilotinib C(max) was 1872 ± 560 ng/mL, which is comparable to steady-state C(max) in CML and gastrointestinal stromal tumour patients receiving twice-daily 400 mg doses. Adverse events observed following either treatment were generally consistent with the known safety profiles of both drugs, and no new safety issues were observed. CONCLUSION: The study results demonstrate that nilotinib has no effect on single-dose warfarin pharmacokinetics and pharmacodynamics. This implies that nilotinib is unlikely to inhibit CYP2C9 activity in human subjects. These findings suggest that warfarin and nilotinib may be used concurrently as needed.

Effect of the proton pump inhibitor esomeprazole on the oral absorption and pharmacokinetics of nilotinib.

Nilotinib (Tasigna), a highly selective and potent BCR-ABL tyrosine kinase inhibitor (TKI), is administered orally and has pH-dependent aqueous solubility, with lower dissolution at higher pH. This study evaluated the effect of esomeprazole on the pharmacokinetics of nilotinib in healthy participants. Twenty-two participants (6 women, 16 men, mean age of 44.9 +/- 12.9 years) were enrolled to receive nilotinib as a single oral 400-mg dose on days 1 and 13 and esomeprazole as 40 mg once daily on days 8 to 13. Serial blood samples were collected up to 72 hours after nilotinib dosing, and nilotinib serum concentrations were determined by a validated liquid chromatography/tandem mass spectrometry assay. Gastric pH was also monitored in all participants. When coadministered with esomeprazole, nilotinib C(max) was decreased by 27% and AUC(0-infinity) decreased by 34%. Nilotinib t(max) was prolonged from 4.0 to 6.0 hours, but t(1/2) was not altered. Mean gastric pH was 1.0 +/- 0.5 at baseline and increased to 2.79 +/- 2.50, 3.98 +/- 2.27, 5.30 +/- 1.70, 5.38 +/- 1.26, and 5.31 +/- 1.42 at predose and 1, 2, 3, and 4 hours after the fifth esomeprazole dose, respectively. These results suggested a modest reduction in the rate and extent of nilotinib absorption by esomeprazole. Nilotinib is a TKI that may be used concurrently with esomeprazole or other proton pump inhibitors.

CYP3A5 but not CYP2D6 polymorphism contributes significantly to the variability in dextropropoxyphene disposition.

This study evaluated the effect of CYP2D6, CYP3A4, and CYP3A5 polymorphisms on dextropropoxyphene disposition in healthy subjects. A total of 14 healthy male Chinese subjects received a single oral dose of a combination tablet of 325 mg of paracetamol and 32.5 mg of dextropropoxyphene. Serial blood samples were collected for up to 24 hours to determine plasma concentrations of paracetamol, dextropropoxyphene, and nordextropropoxyphene by liquid chromatography-tandem mass spectroscopy. CYP2D6, CYP3A4, and CYP3A5 genotyping were performed using polymerase chain reaction-based methods. No CYP3A4 mutant alleles were detected in the study subjects. There were no significant differences (P > .05) in dextropropoxyphene and nordextropropoxyphene pharmacokinetics among CYP2D6 genotypes. In contrast, plasma concentrations of dextropropoxyphene were significantly higher (peak plasma concentration, 54.4 ± 25.5 vs 31.0 ± 10.9 ng/mL; area under the plasma concentration-time curve, 260.8 ± 88.1 vs 142.3 ± 42.4 ng x h/mL, both P < .05) and apparent oral clearance value was significantly lower (2.2 ± 0.9 vs 3.6 ± 1.4 L/h/kg, P < .05) in CYP3A5*3/*3 (n = 8) than CYP3A5*1/*3 (n = 5) subjects. Nordextropropoxyphene exposure also tended to be higher in CYP3A5*3/*3 subjects, but the difference was not statistically significant between the 2 groups. One subject who was identified as a CYP3A5*1/*1 carrier exhibited a very high apparent oral clearance value of 12.5 L/h/kg. No significant difference in paracetamol pharmacokinetics was observed among CYP2D6 or CYP3A5 genotypes. These results suggest that CYP3A5 but not CYP2D6 polymorphisms appear to exert a significant influence on dextropropoxyphene disposition.

Effect of grapefruit juice on the pharmacokinetics of nilotinib in healthy participants.

Nilotinib (Tasigna; Novartis Pharmaceuticals) is a second-generation BCR-ABL tyrosine kinase inhibitor newly approved for the treatment of imatinib-resistant or imatinib-intolerant Philadelphia chromosome positive (Ph+) chronic myeloid leukemia in chronic phase or accelerated phase. This study evaluated the effect of grapefruit juice on the pharmacokinetics of nilotinib in 21 healthy male participants. All participants underwent 2 study periods during which they received a single oral dose of 400 mg nilotinib with 240 mL double-strength grapefruit juice or 240 mL water in a crossover fashion. Serial blood samples were collected for the determination of serum nilotinib concentrations by a validated liquid chromatography/tandem mass spectrometry assay. Concurrent intake of grapefruit juice increased the nilotinib peak concentration (C(max)) by 60% and the area under the serum concentration-time curve (AUC(0-infinity)) by 29% but did not affect the time to reach C(max) or the elimination half-life of nilotinib. The most common adverse events were headache and vomiting, which were mild or moderate in severity, and their frequency appeared to be similar between 2 treatments. Based on the currently available information about nilotinib and the observed extent of increase in nilotinib exposure, concurrent administration of nilotinib with grapefruit juice is not recommended.