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Accurate determination of in vivo circulating concentrations of extracellular adenosine in blood samples is challenging due to the rapid formation and rapid clearance of adenosine in blood. A blood collection protocol was developed based on direct sampling of venous blood into, and instant mixing with, a STOP solution developed to conserve in vivo adenosine concentrations by completely preventing both its formation and clearance in collected blood. Stable isotope labeled AMP and adenosine spiked into blood ex vivo were used in combination with mass spectrometry to evaluate conservation of adenosine and prevention of its formation. A number of approved drugs, including the P2Y12 antagonist ticagrelor, have been described to increase extracellular adenosine. This may contribute to its clinical profile, highlighting the importance of accurate measurement of in vivo adenosine concentrations.A high sensitive ultra performance liquid chromatography-tandem- mass spectrometry (UPLC-tandem-MS) analytical method for plasma adenosine was developed and validated with a lower limit of quantification of 2 nmol/L. The method demonstrated plasma adenosine stability during sample processing and analytical method performance relevant to human blood samples. The final STOP solution proved able to conserve exogenous adenosine and to prevent adenosine formation from exogenous AMP added in vitro to human blood over 15 minutes. The mean endogenous adenosine concentration in plasma prepared from venous blood collected from 10 healthy volunteers was 13 ± 7 nmol/L. Finally, the method was used to demonstrate the previously described concentration-dependent ability of ticagrelor to conserve extracellular adenosine at clinically relevant exposures. In conclusion, we report an optimized sampling protocol and a validated analytical method for accurate measurement of in vivo circulating adenosine concentrations in human blood, suitable for use in clinical trials., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: L. L., S. P. and S. N. are employees of AstraZeneca. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Purpose: This single-dose, randomized, open-label, parallel-group, and crossover study assessed pharmacokinetics (PK), pharmacodynamics (PD), and safety of ticagrelor in subjects on hemodialysis versus healthy subjects., Methods: Hemodialysis subjects were randomized, receiving a single ticagrelor 90-mg dose 1 day post-hemodialysis or just before hemodialysis, with an intervening washout of ≥ 7 days. Healthy subjects (creatinine clearance ≥ 90 mL/min) received a single ticagrelor 90-mg dose. PK, PD (P2Y 12 reaction units [PRU], inhibition of platelet aggregation [IPA]), and safety were evaluated., Results: Twenty-seven subjects (14 hemodialysis, 13 healthy) received ticagrelor. The mean maximum plasma concentration (C max ) and area under the plasma concentration curve from time zero to infinity (AUC 0-∞ ) of ticagrelor were 598.4 ng/mL and 3256.1 ng·h/mL, respectively, in pre-hemodialysis subjects; 560.3 ng/mL and 3015.1 ng·h/mL, respectively, in post-hemodialysis subjects; and 370.8 ng/mL and 2188.8 ng·h/mL, respectively, in healthy subjects. C max and AUC 0-∞ of AR-C124910XX, the active metabolite, were 152.3 ng/mL and 1144.2 ng·h/mL, respectively, in pre-hemodialysis subjects; 130.8 ng/mL and 1127.8 ng·h/mL, respectively, in post-hemodialysis subjects; and 111.7 ng/mL and 1000.4 ng·h/mL, respectively, in healthy subjects. Mean IPA time curves over 24 h post-dose were almost indistinguishable for all three treatments. The greatest reduction in mean PRU occurred approximately 2 h post-dose for all three treatments. No safety or tolerability issues were identified., Conclusion: Hemodialysis resulted in modestly higher exposure to ticagrelor and AR-C124910XX, with no clinically significant effect on PD or tolerability. Accordingly, no dose adjustment is required for hemodialysis patients. Timing of hemodialysis has little impact on ticagrelor PK, or the effect of ticagrelor on IPA.

Objectives: The study sought to assess whether treatment with ticagrelor, as compared with prasugrel and clopidogrel, improves endothelium-dependent dilation throughout the course of the treatment and other vascular biomarkers, including systemic adenosine plasma levels., Background: The in vivo off-target effects of ticagrelor in post-acute coronary syndrome (ACS) patients remain poorly characterized., Methods: Fifty-four stable post-ACS patients were sequentially exposed to each of the 3 oral P2Y 12 inhibitors following a 3-period balanced Latin square crossover design with 4 weeks per treatment in 5 European centers. The primary endpoint was the assessment of endothelial function with pulse amplitude tonometry and expressed as reactive hyperemia index at treatment steady state. Secondary endpoints included reactive hyperemia index after loading or before maintenance regimen, systemic adenosine plasma levels, a wide set of vascular biomarkers, and ticagrelor or AR-C124910XX plasma levels throughout each ticagrelor period. In 9 patients, the evaluation of endothelial function was performed simultaneously by pulse amplitude tonometry and flow-mediated dilation., Results: Reactive hyperemia index did not differ after ticagrelor (1.970 ± 0.535) as compared with prasugrel (2.007 ± 0.640; p = 0.557) or clopidogrel (2.072 ± 0.646; p = 0.685), nor did systemic adenosine plasma levels or vascular biomarkers at any time points. P2Y 12 platelet reactivity units were lower after ticagrelor as compared with clopidogrel at all time points and after maintenance dose as compared with prasugrel. Flow-mediated dilation did not differ after the maintenance dose of ticagrelor as compared with clopidogrel and prasugrel., Conclusions: Ticagrelor did not improve endothelial function or increased systemic adenosine plasma levels as compared with prasugrel and clopidogrel in stabilized patients who suffered from an ACS. (Hunting for the Off-Target Properties of Ticagrelor on Endothelial Function in Humans [HI-TECH]; NCT02587260)., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: The manuscript was mainly aimed to evaluate effects of food and gender on the pharmacokinetics of ticagrelor and its main active metabolite AR-C124910XX in healthy Chinese subjects observed in the bioequivalence studies of the two formulations of ticagrelor tablets., Materials and Methods: The single-dose, two-sequence, two-period and crossover studies were respectively conducted under fasting and fed conditions. Plasma samples were analyzed by an HPLC-MS/MS method. Log-transformed pharmacokinetic parameters of ticagrelor and AR-C124910XX obtained from the trials were compared by the mean of two one-sided t-test., Results: Pharmacokinetic parameters of the two formulations were evaluated. The mean ticagrelor tmax value was delayed by 0.28 - 0.53 hours owing to meals. A 21.6 - 24.0% (p < 0.05) increase in the mean ticagrelor AUC* (body weight-normalized AUC) value was measured (fed vs. fasting). For AR-C124910XX, the mean T1/2 value was delayed by 0.84 - 1.33 hours (p < 0.05) due to meals. A 52.0 - 55.8% (p < 0.05) decrease in the mean Cmax* (body weight-normalized Cmax) value and a 15.6 - 16.9% (p < 0.05) decrease in the mean AUC* value were observed (fed vs. fasting). The female subjects exhibited higher exposures to ticagrelor and AR-C124910XX than the male subjects. Compared with other populations, the Chinese subjects in this study experienced a greater decrease in Cmax of AR-C124910XX due to meals. 21 adverse events of mild intensity occurred over the study periods., Conclusion: The studies showed food effects on the absorption of ticagrelor and the formation of AR-C124910XX, and gender effects on exposures to the drug after single oral-dose administration.
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Background: Ticagrelor, the first reversible P2Y 12 receptor antagonist, exhibits faster onset and offset of antiplatelet effects and more consistent platelet inhibition than clopidogrel in both healthy subjects and patients with stable coronary artery disease., Objective: The objectives of this study were to establish a population pharmacokinetics (PK) and pharmacodynamics (PD) model of ticagrelor and to provide a theoretical basis for the optimization of ticagrelor treatment in clinic., Methods: A single oral dose of 180 mg ticagrelor was administered to 14 healthy male subjects in a randomized study. Common single-nucleotide polymorphisms (SNPs) in biotransformation enzymes CYP3A4 and CYP3A5 (CYP3A4*1G and CYP3A5*3) were genotyped by PCR-direct sequencing. Blood samples were collected to measure plasma concentrations of ticagrelor and its active metabolite AR-C124910XX and maximal platelet inhibition. Various models were evaluated to characterize the pharmacokinetics of ticagrelor and AR-C124910XX as well as their PK-PD relationship. Covariates that may potentially affect PK or PD of ticagrelor and AR-C124910XX were included and assessed. Simulation for dosage regimen was performed based on the final PK-PD model., Results: Ticagrelor and AR-C124910XX PK were best described by a two-compartment model with first-order transit absorption model. CYP3A4*1G increased clearance for AR-C124910XX, but had no significant effect on ticagrelor clearance. The relationship between concentration and platelet response of ticagrelor was best described by a turnover model. Simulation results indicated that a lower dosage regimen of 30 mg maintenance dose (MD) could produce an anticipated anti-platelet response in comparison to the routine clinical dosage regimen (180 mg loading dose (LD), 90 mg MD)., Conclusion: Our study developed a population PK-PD model for ticagrelor and further simulation for dosage regimen was performed based on the final model. Compared to the current recommended dosage regimen (180 mg LD, 90 mg MD), our simulation result of a relatively lower dose (30 mg MD) could also obtain an acceptable anti-platelet response, which may provide a reference for further dosage regimen design in Chinese population.

Background: Pivotal clinical trials found that ticagrelor reduced ischaemic complications to a greater extent than clopidogrel, and also that the benefit gradually increased with the reduction in creatinine clearance. However, the underlying mechanisms remains poorly explored., Methods: This was a single-centre, prospective, randomized clinical trial involving 60 hospitalized Adenosine Diphosphate (ADP) P2Y12 receptor inhibitor-naïve patients with chronic kidney disease (CKD) (estimated glomerular filtration rate <60 ml min -1 1.73 m -2 ) and non-ST-elevation acute coronary syndromes (NSTE-ACS). Eligible patients were randomly assigned in a 1:1 ratio to receive ticagrelor (180 mg loading dose, then followed by 90 mg twice daily) or clopidogrel (600 mg loading dose, then followed by 75 mg once daily). The primary endpoint was the P2Y12 reactive unit (PRU) value assessed by VerifyNow at 30 days. The plasma concentrations of ticagrelor and clopidogrel and their active metabolites were measured in the first 10 patients in each group at baseline, and at 1 h, 2 h, 4 h, 8 h, 12 h and 24 h after the loading dose., Results: Baseline characteristics were well matched between the two groups. Our results indicated a markedly lower PRU in patients treated with ticagrelor vs. clopidogrel at 30 days (32.6 ± 11.29 vs. 203.7 ± 17.92; P < 0.001) as well as at 2 h, 8 h and 24 h after the loading dose (P < 0.001). Ticagrelor and its active metabolite AR-C124910XX showed a similar time to reach maximum concentration (C max ) of 8 h, with the maximum concentration (C max ) of 355 (242.50-522.00) ng ml -1 and 63.20 (50.80-85.15) ng ml -1 , respectively. Both clopidogrel and its active metabolite approached the C max at 2 h, with a similar C max of 8.67 (6.64-27.75) ng ml -1 vs. 8.53 (6.94-15.93) ng ml -1 ., Conclusion: Ticagrelor showed much more potent platelet inhibition in comparison with clopidogrel in patients with CKD and NSTE-ACS., (© 2017 The British Pharmacological Society.)

The pharmacokinetics after a 180-mg loading dose (LD) of ticagrelor has not been thoroughly investigated in NSTEMI patients. We aimed to compare the ticagrelor uptake and on-treatment platelet reactivity between non-ST-segment elevation myocardial infarction (NSTEMI) patients and a control group of patients with stable coronary artery disease (SCAD) undergoing elective percutaneous coronary intervention. We performed an observational, prospective, single-center study including 40 NSTEMI patients and 20 SCAD controls. Key exclusion criteria included ongoing opioid treatment. Both groups received a 180-mg ticagrelor LD, and blood samples were taken pre-dose and 1, 2, 3, 4, 5, and 6 hours post-LD. Plasma concentrations of ticagrelor and its active metabolite AR-C124910XX were determined by validated methods. Platelet aggregation was tested using ADP-induced multiple electrode aggregometry. The primary endpoint was the time to maximal ticagrelor concentration (T max ). Clinical trial registration identifier number: NCT02292277. None of the pharmacokinetic variables differed significantly between the groups, including the T max of ticagrelor (2.0h [1.0-3.0] versus 2.0h [2.0-3.0], p = 0.393) and the active metabolite AR-C124910XX (3.0 [2.0-4.0] versus 3.0 [2.5-4.0], p = 0.289). High on-treatment platelet reactivity (HPR) was defined as > 46 aggregation units and was at one hour seen in 15% of the NSTEMI patients versus 10% of the controls (p = 1.0). At two hours post the 180-mg ticagrelor LD, 3% of the NSTEMI patients had HPR compared with none of the controls (p = 1.0). In conclusion, the uptake of ticagrelor was not significantly slower in NSTEMI patients not receiving opioids compared with the SCAD controls, leading to adequate onset of platelet inhibition in both groups.

Objective: The population pharmacokinetics of ticagrelor and its active metabolite AR-C124910XX were characterized following ticagrelor 60 mg or 90 mg twice daily oral long-term treatment in 4,426 patients with a history of myocardial infarction., Methods: The ticagrelor and AR-C124910XX plasma concentration-time data were described by one-compartment models with first-order absorption or metabolite formation and elimination., Results: Systemic exposure to ticagrelor and AR-C124910XX were stable over time. Ticagrelor apparent clearance (CL/F) was 17 L/h for the 60-mg and 15.4 L/h for the 90-mg dose. The CL/F of AR-C124910XX was 11.1 L/h for the 60-mg and 9.95 L/h for the 90-mg dose. Both ticagrelor and AR-C124910XX CL/F were independently influenced by body weight, sex, age, smoking, and Japanese ethnicity. Female sex and age > 75 years were the only categorical covariates, having more than 20% effect on AR-C124910XX CL/F. Ticagrelor CL/F was 6% higher and 11% lower, whereas AR-C124910XX CL/F was 26% higher and 34% lower for patients weighing 110 and 50 kg, respectively, compared with an 83 kg patient., Conclusions: The small differences in exposure to both ticagrelor and AR-C124910XX between demographic subgroups were in accordance with the consistent efficacy and safety outcomes observed across the population. The results were similar to those observed previously in patients with acute coronary syndromes.
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We have developed and validated a rapid, selective and sensitive method using high-performance liquid chromatography-tandem mass spectrometry (MS) for the quantification of ticagrelor and all of its as-yet-identified metabolites in human plasma and urine. For the analysis of ticagrelor, its metabolites and the internal standard (IS) plasma samples were processed by liquid-liquid extraction using ethyl acetate and urine was processed by protein precipitation. Separations were performed on an Ultimate XB-C18 column (2.1 mm × 150 mm, 3 μm), using aqueous ammonium acetate (0.025 mM)/acetonitrile (35 : 65, v:v) as the mobile phase. Ticagrelor and all 11 metabolites were eluted within 4.5 min. Quantification was performed using electrospray ionization, operating in negative ion mode. The ticagrelor and metabolite M8 (AR-C124910XX) responses were optimized at the m/z 521.2 → 361.2 and m/z 477.2 → 361.1 transitions, respectively. The assay was validated over the linear range of 0.5-2,000 ng/mL for ticagrelor and M8. The intra- and inter-assay precisions were ≤14.6% for ticagrelor and ≤14.7% for M8, respectively. The matrix effects of plasma and urine were in the range of 98.3-110.7% for ticagrelor and 102.1-112.3% for M8. The relative quantification of other metabolites was performed by assessing the ratio of metabolite to IS peaks. The newly developed method was successfully used in a pharmacokinetic study characterizing ticagrelor metabolism in human volunteers., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

This review summarizes current knowledge concerning "nonplatelet effects of P2Y12 receptor antagonist ticagrelor. We show the experimental and clinical evidence that ticagrelor increases plasma concentration of adenosine as a potential mechanism of additive effects of ticagrelor. In addition, we sought to compare the clinical profile of ticagrelor with pharmacological effects of adenosine and discuss from this point of view the effects of ticagrelor on vascular tone, cardiac electrophysiology, ischemia/reperfusion injury, immunity and inflammatory reactions, peripheral nerves.

Objective: The objective of this study was to assess the pharmacokinetic and pharmacodynamic behavior of ticagrelor administered either as crushed (in the semi-upright sitting position) or as integral (in the supine position) tablets in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI)., Methods: We randomized 20 patients to ticagrelor 180 mg either as 2 integral tablets administered in the supine position (standard administration) or as 2 tablets crushed and dispersed, administered in the semi-upright sitting position. Blood samples were drawn for pharmacokinetic and pharmacodynamic assessment at randomization (0 h) and at 0.5, 1, 2, and 4 h., Results: At 1 h, ticagrelor plasma exposure and area under the plasma concentration-time curve from time zero to 1 h (AUC1) (co-primary endpoints) were higher in the crushed versus integral tablets group (median 586 vs. 70.1 ng/mL and 234 vs. 24.4 ng·h/mL, respectively), with a ratio of adjusted geometric means (95% confidence interval [CI]) of 12.67 (2.34-68.51) [p = 0.005] and 19.28 (3.51-106.06) [p = 0.002], respectively. Time to maximum plasma concentration was shorter in the crushed versus integral tablets group (median 2 vs. 4 h), with a ratio of adjusted geometric means (95% CI) of 0.69 (0.49-0.97) [p = 0.035]. Parallel findings were observed with AR-C124910XX (active metabolite). Platelet reactivity (VerifyNow(®)) at 1 h was lower with crushed versus standard administration with least squares estimates mean difference (95% CI) of 92 (-158.4 to 26.6) P2Y12 reaction units (p = 0.009)., Conclusions: In patients with STEMI undergoing primary PCI, ticagrelor crushed tablets administered in the semi-upright sitting position seems to lead to a faster-compared with standard administration-absorption, with stronger antiplatelet activity within the first hour., Trial Registration: ClinicalTrials.gov identifier: NCT02046486.

Aims: Ticagrelor, a direct-acting P2Y12-receptor antagonist, is rapidly absorbed and partly metabolized to the major metabolite AR-C124910XX (ARC). To identify single-nucleotide polymorphisms (SNPs) associated with pharmacokinetics of ticagrelor and clinical outcomes, we performed a genome-wide association study (GWAS) in patients treated with ticagrelor in the PLATO trial., Methods and Results: A two-stage design was used for the GWAS with discovery (discovery phase: n = 1812) and replication cohorts (replication phase: n = 1941). The steady-state area under the curve (AUCss) values, estimated by the population pharmacokinetic (PK) models, were log transformed and analysed on a genome-wide scale using linear regression. SNPs were analysed against clinical events using Cox-regression in 4990 patients. An SNP (rs113681054) in SLCO1B1 was associated with levels of ticagrelor (P = 1.1 × 10(-6)) and ARC (P = 4.6 × 10(-13)). This SNP is in linkage disequilibrium with a functional variant (rs4149056) that results in decreased OATP1B1 transporter activity. Ticagrelor levels were also associated with two independent SNPs (rs62471956, P = 7.7 × 10(-15) and rs56324128, P = 9.7 × 10(-12)) in the CYP3A4 region. Further, ARC levels were associated with rs61361928 (P = 3.0 × 10(-14)) in UGT2B7. At all loci, the effects were small. None of the identified SNPs that affected ticagrelor PK were associated with the primary composite outcome (cardiovascular death myocardial infarction, and stroke), non-CABG-related bleeds or investigator-reported dyspnoea., Conclusion: In patients with ACS, ticagrelor pharmacokinetics is influenced by three genetic loci (SLCO1B1, UGT2B7, and CYP3A4). However, the modest genetic effects on ticagrelor plasma levels did not translate into any detectable effect on efficacy or safety during ticagrelor treatment., Clinical Trial Registration: NCT00391872., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)

Background: Ticagrelor is an oral platelet P2Y12 receptor antagonist which is recommended for patients suffering from myocardial infarction, both with and without persistent ST segment elevation. Morphine is the first choice drug in pain alleviation in the same clinical subset. Recently a possible negative influence of morphine on the pharmacokinetics and antiplatelet effects of P2Y12 receptor blockers has been postulated., Methods/design: The IMPRESSION study is a phase IV, single center, randomized, double-blind, placebo-controlled clinical trial that is designed to assess the influence of morphine on the pharmacokinetics and pharmacodynamics of ticagrelor in patients with myocardial infarction. The study is planned to include up to 100 patients with myocardial infarction who will be randomized into one of two arms in a 1:1 ratio. Subjects in the intervention arm prior to the loading dose of ticagrelor (180 mg) will receive morphine (5 mg) intravenously, whereas patients in the control arm will receive a placebo prior to the loading dose of ticagrelor (180 mg). The pharmacokinetics of ticagrelor and its active metabolite (AR-C124910XX) will be assessed by liquid chromatography mass spectrometry. Platelet function testing in each patient will be performed using up to four different methods (platelet vasodilator-stimulated phosphoprotein assay, multiple electrode aggregometry, VerifyNow, and light transmission aggregometry)., Discussion: This study is expected to provide essential evidence-based data on the impact of morphine on the absorption of ticagrelor in patients with myocardial infarction as well as to shed some light on the suspected connection between morphine use and antiplatelet activity of ticagrelor in the same group of patients., Trial Registration: ClinicalTrials.gov identifier: NCT02217878 (14 August 2014).

Managing bleeding in patients receiving P2Y12 inhibitors is challenging. Few data are available regarding the efficacy of platelet transfusion in patients treated with prasugrel or ticagrelor. The aim of this study was to evaluate the minimal amount of platelet supplementation (in terms of ratio of non-inhibited platelets to inhibited platelets) necessary to restore platelet reactivity in platelet-rich plasma (PRP) of patients treated with aspirin and a prasugrel or ticagrelor loading dose for an acute coronary syndrome. PRP samples from patients were mixed ex vivo with increasing proportions of pooled PRP from healthy volunteers. Platelet reactivity was challenged with adenosine diphosphate (ADP), arachidonic acid, collagen or thrombin receptor activating peptide using light transmission aggregometry. The primary endpoint was the proportion of patient samples recovering an ADP-induced maximal aggregation (ADP-Aggmax) value above 40%. In patients treated with prasugrel (n = 32), ADP-Aggmax increased progressively with supplements of pooled PRP, with an average increase of 7.9% (95% CI [7.1; 8.8], p < 0.001) per each 20% increase in the ratio of non-inhibited platelets to inhibited platelets. A ratio of 60% was associated with 90% of patients reaching the primary endpoint. In patients treated with ticagrelor (n = 15), ADP-Aggmax did not significantly increase with any level of supplements. In conclusions, ex vivo addition of non-inhibited platelets significantly improved ADP-Aggmax in patients treated with prasugrel with a dose-dependent effect. There was no evidence of such a reversal in patients treated with ticagrelor. These results suggest that platelet transfusion may be more effective in blunting bleeding in patients treated with prasugrel, than those treated with ticagrelor.

This randomized, active-controlled, double-blind study assessed the pharmacodynamics, pharmacokinetics and safety of ticagrelor in Japanese patients and a smaller cohort of non-Japanese Asian patients. The study recruited patients aged 20-80 years who had received aspirin 75-100 mg/day for ≥2 weeks and had percutaneous coronary intervention or acute coronary syndrome >3 months previously. Patients received 4 weeks' treatment with ticagrelor 45 mg bid, ticagrelor 90 mg bid or clopidogrel 75 mg qd (all with aspirin). The inhibition of platelet aggregation (IPA, final-extent) and pharmacokinetics of ticagrelor were assessed on days 1 and 28. Overall, 139 Asian patients were randomized (ticagrelor 45 mg bid, n = 50; ticagrelor 90 mg bid, n = 43; clopidogrel, n = 46) of whom 118 were Japanese. Mean final-extent IPA was greater with ticagrelor 90 mg bid versus ticagrelor 45 mg bid and with both ticagrelor doses versus clopidogrel. At the end of the dosing interval on day 28, mean final-extent IPA was 10.0% higher (95% confidence interval 0.5-19.5%) for ticagrelor 90 mg bid versus ticagrelor 45 mg bid, 15.1% higher (5.8-24.4%) for ticagrelor 45 mg bid versus clopidogrel, and 25.1% higher (15.5-34.7%) for ticagrelor 90 mg bid versus clopidogrel. In Japanese patients, exposure to ticagrelor and its active metabolite AR-C124910XX increased dose-proportionally. The safety profile of ticagrelor was consistent with previous studies. Ticagrelor was associated with enhanced IPA versus clopidogrel in Japanese patients.

Purpose: Ticagrelor is a reversibly binding P2Y12 receptor antagonist used clinically for the prevention of atherothrombotic events in patients with acute coronary syndromes (ACS). Ticagrelor has been shown in vitro to be a weak inhibitor of cytochrome P-450 (CYP) 2D6, a clinically important enzyme for the metabolism of many drugs. This study assessed the effects of coadministration of ticagrelor on the pharmacokinetics of the CYP2D6 substrate venlafaxine. The impact of venlafaxine on ticagrelor pharmacokinetic parameters was also investigated., Methods: Healthy subjects (N = 22) received a single 180-mg oral dose of ticagrelor on days 1 and 9 and oral doses of venlafaxine on day 4 (37.5 mg BID) and days 5 through 10 (75 mg BID). Plasma concentrations of ticagrelor, venlafaxine, and their metabolites (AR-C124910XX and O-desmethylvenlafaxine [ODV], respectively) were quantified for pharmacokinetic analyses. Safety and tolerability were assessed throughout the study., Findings: Overall, 19 of 25 subjects were male; 14 were white, 10 were black, and 1 was Asian. Mean (SD) age was 26 (6) years, and mean (SD) body mass index was 24.3 (2.9) kg/m(2). Ticagrelor had no effect on overall exposure to venlafaxine, as assessed by the AUC0-τ (geometric least squares mean ratio, 110.32 ng · h/mL [90% CI, 106.27-114.52]). Venlafaxine Cmax was increased by 22% in the presence of ticagrelor (121.83 ng/mL [90% CI, 111.80-132.75]). ODV AUC0-τ and Cmax were unaffected by coadministration with ticagrelor (98.71 ng · h/mL [90% CI, 96.61-100.85] and 101.44 ng/mL [90% CI, 98.34-104.65], respectively). Venlafaxine had no effect on the Cmax or AUC0-∞ of ticagrelor (96.54 ng/mL [90% CI, 85.03-109.61] and 89.67 ng · h/mL [90% CI, 82.78-97.14]) or AR-C124910XX (106.39 ng/mL [90% CI, 96.10-117.78] and 106.32 ng · h/mL [90% CI, 97.28-116.21], respectively). Ticagrelor and venlafaxine were well tolerated whether given alone or in combination., Implications: Ticagrelor had no clinically relevant effect on the plasma levels of venlafaxine and its CYP2D6-generated active metabolite, ODV. On the basis of these data, ticagrelor is not expected to affect CYP2D6-mediated drug metabolism to a clinically relevant extent. Venlafaxine had no effect on the pharmacokinetics of ticagrelor., (Copyright © 2014 Elsevier HS Journals, Inc. All rights reserved.)

Objectives: Two studies assessing ticagrelor pharmacokinetics, pharmacodynamics, and tolerability in healthy Japanese and Caucasian volunteers., Materials and Methods: Single-ascending dose (SAD) study: Japanese (n = 20) and Caucasians (n = 20) received single doses of ticagrelor (50, 100, 200, 300, 400, and 600 mg) or placebo. Multiple-ascending dose (MAD) study: Japanese (n = 36) and Caucasians (n = 36) received single doses of 100 mg or 300 mg ticagrelor (day 1), twice-daily 100 mg or 300 mg ticagrelor, or placebo (days 4 – 9), and single doses of 100 mg or 300 mg ticagrelor (day 10)., Results: Exposure to ticagrelor and its active metabolite, AR-C124910XX, was generally higher in Japanese vs. Caucasians. In the SAD study, area under the plasma concentration-time curve (AUC) values were 33% (ticagrelor) and 55% (AR-C124910XX) greater in Japanese vs. Caucasians following 600 mg ticagrelor. In the MAD study, AUC values of ticagrelor and AR-C124910XX following multiple doses of ticagrelor 100 mg and 300 mg were statistically significantly greater (33 - 48%) in Japanese vs. Caucasians. In both groups, mean peak inhibition of platelet aggregation was > 86% after single doses (>= 100 mg ticagrelor) and > 84% after multiple doses. Bleeding times were >= 60 minutes in more Japanese than Caucasians with multiple dosing of 100 mg and 300 mg ticagrelor Adverse events were similar between groups (mild-to-moderate intensity)., Conclusions: The pharmacokinetics and tolerability of ticagrelor were broadly similar in Japanese and Caucasians, although exposure was slightly greater in Japanese volunteers. Ticagrelor was generally well tolerated.

Objectives: This study aimed to investigate the impact of ticagrelor on adenosine plasma concentration (APC) in acute coronary syndrome (ACS) patients., Background: Ticagrelor is a direct-acting P2Y12-adenosine diphosphate receptor blocker. The clinical benefit of ticagrelor compared with clopidogrel in ACS patients suggests that the drug has non-platelet-directed properties. Animal and in vitro models suggested that the "pleiotropic" properties of ticagrelor may be related to an interaction with adenosine metabolism., Methods: We prospectively randomized 60 ACS patients to receive ticagrelor or clopidogrel. The APC was measured by liquid chromatography. To assess the mechanism of APC variation, we measured adenosine deaminase concentration, adenosine uptake by red blood cells, and cyclic adenosine monophosphate production by cells overexpressing adenosine receptors. The P2Y12-adenosine diphosphate receptor blockade was assessed by the vasodilator-stimulated phosphoprotein index., Results: Patients receiving ticagrelor had significantly higher APC than patients receiving clopidogrel (1.5 μM [interquartile range: 0.98 to 1.7 μM] vs. 0.68 μM [interquartile range: 0.49 to 0.78 μM]; p < 0.01). The APC was not correlated with vasodilator-stimulated phosphoprotein (p = 0.16). Serum-containing ticagrelor inhibited adenosine uptake by red blood cells compared with clopidogrel or controls (p < 0.01 for both comparisons). Adenosine deaminase activity was similar in serum of patients receiving clopidogrel or ticagrelor (p = 0.1). Ticagrelor and clopidogrel had no direct impact on adenosine receptors (p = not significant)., Conclusions: Ticagrelor increases APC in ACS patients compared with clopidogrel by inhibiting adenosine uptake by red blood cells., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Purpose: Ticagrelor is a reversibly binding P2Y12 receptor antagonist for the prevention of atherothrombotic events in patients with acute coronary syndrome. Previous in vitro studies showed that ticagrelor is a substrate and inhibitor of P-glycoprotein (ABCB1). Therefore, we examined the potential interaction between digoxin, a P-glycoprotein substrate, and ticagrelor by evaluating the pharmacokinetics, safety, and tolerability., Methods: This was a randomized, double-blind, two-period crossover study in healthy volunteers (n = 20). Pharmacokinetic parameters of digoxin and ticagrelor were evaluated following co-administration of ticagrelor 400 mg qd or placebo on days 1-16, and digoxin (0.25 mg bid on day 6 and 0.25 mg qd on days 7-14)., Results: Co-administration of ticagrelor increased the digoxin maximum plasma concentration by 75 %, from 1.8 ng/ml to 3.0 ng/ml (Gmean ratio [GMR] 1.75 [95 % CI, 1.52-2.01]); minimum plasma concentration by 31 %, from 0.5 ng/ml to 0.7 ng/ml (GMR 1.31, 1.13-1.52); and mean area under the curve by 28 %, from 16.8 ng · h/ml to 21.0 ng · h/ml (GMR 1.28, 1.12-1.46), compared with placebo. Renal clearance of digoxin was unaffected by the presence of ticagrelor. Digoxin had no effect on the pharmacokinetics of ticagrelor or its active metabolite, AR-C124910XX. Co-administration of ticagrelor and digoxin was well tolerated., Conclusions: Collectively, these results indicate that ticagrelor is a weak inhibitor of the P-glycoprotein transporter. Based on these findings, it is recommended that serum concentrations of drugs like digoxin (P-glycoprotein transporter substrates with a narrow therapeutic range) are monitored when initiating or changing ticagrelor therapy.

Background: Ticagrelor, a P2Y12 antagonist, is an antiplatelet agent approved for the treatment of acute coronary syndromes; it also inhibits adenosine uptake by erythrocytes and other cells., Objective: To test whether ticagrelor inhibits platelet aggregation (PA) in whole blood (WB) by increasing the extracellular levels of adenosine, which inhibits PA via the A2A receptor., Methods: Collagen-induced PA was measured in WB or platelet-rich plasma (PRP) from 50 healthy subjects and two patients with inherited P2Y12 deficiency, in presence/absence of adenosine concentrations that by themselves marginally affected PA in WB, and ZM241385 (A2A antagonist). The effects of ticagrelor, the active metabolite of prasugrel (PAM) (P2Y12 antagonist), and dipyridamole (adenosine uptake inhibitor) on PA and on adenosine clearance in WB were compared., Results: For PA in WB, adenosine contributed to drug-induced inhibition of PA; the adenosine contribution was similar for dipyridamole and ticagrelor but was significantly greater for ticagrelor than for PAM (P < 0.01). For PA in PRP (no adenosine uptake by erythrocytes), adenosine contributed to inhibition of PA in the presence/absence of all tested drugs. ZM241385 reversed the inhibition by adenosine in WB and PRP. Similar results were obtained with WB and PRP from P2Y12 -deficient patients. Adenosine (7.1 μmol L(-1) ) added to WB, was detectable for 0.5 min in the presence of vehicle or PAM, for 3-6 min in the presence of ticagrelor, and for > 60 min in the presence of dipyridamole., Conclusion: This study provides the first evidence of an additional antiplatelet mechanism by ticagrelor, mediated by the induced increase of adenosine levels., (© 2013 International Society on Thrombosis and Haemostasis.)

Purpose: Ticagrelor, a reversibly binding oral P2Y12 receptor antagonist, is predominantly metabolized by cytochrome P450 3A and both the parent compound and its active metabolite AR-C124910XX are substrates of P-glycoprotein. Rifampicin was used to assess the effects of CYP3A and P-glycoprotein induction on the single-dose pharmacokinetics and pharmacodynamics of ticagrelor., Methods: Healthy volunteers received a single 180 mg oral dose of ticagrelor on days 1 and 15, and a once-daily 600 mg dose of rifampicin on days 4-17. Ticagrelor and AR-C124910XX plasma concentrations were quantified for pharmacokinetic analysis (n = 14); inhibition of platelet aggregation (IPA) was also assessed (n = 14)., Results: Compared with administration of ticagrelor alone, co-administration of ticagrelor and rifampicin significantly decreased the maximum plasma concentration (Cmax) of ticagrelor from 1091 to 297.8 ng/ml, area under the plasma concentration-time curve from time zero to infinity (AUC) of ticagrelor from 6225 to 864.0 ng.h/ml, and also decreased plasma half-life of ticagrelor from 8.4 to 2.8 h; reductions of 73 %, 86 % and 67 % respectively. With rifampicin, AR-C124910XX Cmax was unaffected, AUC was significantly decreased by 46 %, and metabolite to parent ratio for AUC increased fourfold. Although maximal IPA was unaffected, offset of ticagrelor-mediated IPA was more rapid in the presence of rifampicin; a significant reduction (27 %) in the area under the effect curve between 0 and 24 h was observed following co-administration with rifampicin., Conclusion: Co-administration with rifampicin reduced ticagrelor exposure and resulted in a more rapid offset of ticagrelor-mediated IPA. Co-administration of strong CYP3A/P-glycoprotein inducers with ticagrelor should be discouraged.

Ticagrelor is a reversibly binding and selective oral P2Y(12) antagonist, developed for the prevention of atherothrombotic events in patients with acute coronary syndromes. The disposition and metabolism of [(14)C]ticagrelor was investigated in mice, rats, and marmosets to demonstrate that these preclinical toxicity species showed similar metabolic profiles to human. Incubations with hepatocytes or microsomes from multiple species were also studied to compare with in vivo metabolic profiles. The routes of excretion were similar for both oral and intravenous administration in mice, rats, and marmosets with fecal excretion being the major elimination pathway accounting for 59 to 96% of the total radioactivity administered. Urinary excretion of drug-related material accounted for only 1 to 15% of the total radioactivity administered. Milk samples from lactating rats displayed significantly higher levels of total radioactivity than plasma after oral administration of ticagrelor. This demonstrated that ticagrelor and/or its metabolites were readily transferred into rat milk and that neonatal rats could be exposed to ticagrelor-related compounds via maternal milk. Ticagrelor and active metabolite AR-C124910 (loss of hydroxyethyl side chain) were the major components in plasma from all species studied and similar to human plasma profiles. The primary metabolite of ticagrelor excreted in urine across all species was an inactive metabolite, AR-C133913 (loss of difluorophenylcyclopropyl group). Ticagrelor, AR-C124910, and AR-C133913 were the major components found in feces from the three species examined. Overall, in vivo metabolite profiles were qualitatively similar across all species and consistent with in vitro results.

Ticagrelor is the first direct acting reversibly binding oral platelet P2Y(12) receptor antagonist. The parent molecule and the main metabolite (AR-C124910XX) are both able to block adenosine diphosphate-induced receptor signaling with similar potency. Drug binding to plasma proteins reduces free drug available for pharmacologic activity. Therefore, assessing unbound drug is important for interpretation of pharmacokinetic/pharmacodynamic findings. This paper describes the development and validation of an equilibrium dialysis/LC-MS/MS method for measuring unbound ticagrelor and AR-C124910XX in human plasma. Plasma samples (200μl) were dialysed against phosphate buffered saline (37 °C, 24h) in 96-well dialysis plates to separate unbound analytes. Drug-protein binding alterations during dialysis were minimized by maintaining physiologic conditions (pH 7.4, 37 °C). Ticagrelor and AR-C124910XX were quantified in dialysates (unbound fraction), retentates and plasma (total concentration) using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) methods. Calibration curves were established for the retentate and plasma (total concentration) in the ranges 5-5000 ng/ml (ticagrelor) and 2.5-2500 ng/ml (AR-C124910XX), and for the dialysate in the range 0.25-100 ng/ml (both analytes). Both ticagrelor and AR-C124910XX were highly protein bound (>99.8%), i.e. unbound fraction <0.2%. Yet, the methodology was successfully applied to determine unbound concentrations of ticagrelor and AR-C124910XX in clinical samples., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Ticagrelor, a P2Y₁₂ receptor antagonist that inhibits ADP-induced platelet aggregation (IPA), has demonstrated improved outcomes in patients with acute coronary syndromes compared with clopidogrel. Because ticagrelor undergoes extensive hepatic elimination, this study evaluated the effect of mild hepatic impairment on its pharmacokinetics, pharmacodynamics, and safety. A single oral 90-mg ticagrelor dose was administered to volunteers with and without hepatic impairment (10 with Child-Pugh class A; 10 with normal liver function). Absorption of ticagrelor and formation of its active metabolite, AR-C124910XX, were rapid in both groups. Ticagrelor exposure was higher in hepatically impaired volunteers (maximum concentration [C(max)] 12%; area under the plasma concentration-time curve from time 0 to infinity [AUC] 23%) compared with controls. AR-C124910XX exposure was also higher in hepatic impairment (C(max) 17%; AUC 66%). Ticagrelor is highly protein bound (>99.8%); the unbound fraction in plasma was comparable in volunteers with hepatic impairment and controls. Overall, IPA parameters were not significantly different between groups, and similar IPA-concentration profiles were observed. Ticagrelor was well tolerated in both groups, and no adverse events were reported. In conclusion, mild hepatic impairment resulted in modestly higher exposure to ticagrelor and AR-C124910XX, without subsequent effects on pharmacodynamics or tolerability. Based on these data, no ticagrelor dosage adjustment is needed in patients with mild hepatic impairment.