Cangrelor, Tirofiban, and Chewed or Standard Prasugrel Regimens in Patients With ST-Segment-Elevation Myocardial Infarction: Primary Results of the FABOLUS-FASTER Trial.

BACKGROUND: Standard administration of newer oral P2Y12 inhibitors, including prasugrel or ticagrelor, provides suboptimal early inhibition of platelet aggregation (IPA) in patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention. We aimed to investigate the effects of cangrelor, tirofiban, and prasugrel, administered as chewed or integral loading dose, on IPA in patients undergoing primary percutaneous coronary intervention. METHODS: The FABOLUS-FASTER trial (Facilitation Through Aggrastat or Cangrelor Bolus and Infusion Over Prasugrel: A Multicenter Randomized Open-Label Trial in Patients with ST-Elevation Myocardial Infarction Referred for Primary Percutaneous Intervention) is an investigator-initiated, multicenter, open-label, randomized study. A total of 122 P2Y12-naive patients with ST-segment-elevation myocardial infarction were randomly allocated (1:1:1) to cangrelor (n=40), tirofiban (n=40) (both administered as bolus and 2-hour infusion followed by 60 mg of prasugrel), or 60-mg loading dose of prasugrel (n=42). The latter group underwent an immediate 1:1 subrandomization to chewed (n=21) or integral (n=21) tablets administration. The trial was powered to test 3 hypotheses (noninferiority of cangrelor compared with tirofiban using a noninferiority margin of 9%, superiority of both tirofiban and cangrelor compared with chewed prasugrel, and superiority of chewed prasugrel as compared with integral prasugrel, each with α=0.016 for the primary end point, which was 30-minute IPA at light transmittance aggregometry in response to 20 µmol/L adenosine diphosphate. RESULTS: At 30 minutes, cangrelor did not satisfy noninferiority compared with tirofiban, which yielded superior IPA over cangrelor (95.0±8.9 versus 34.1±22.5; P<0.001). Cangrelor or tirofiban were both superior to chewed prasugrel (IPA, 10.5±11.0; P<0.001 for both comparisons), which did not provide higher IPA over integral prasugrel (6.3±11.4; P=0.47), despite yielding higher prasugrel active metabolite concentration (ng/mL; 62.3±82.6 versus 17.1±43.5; P=0.016). CONCLUSIONS: Cangrelor provided inferior IPA compared with tirofiban; both treatments yielded greater IPA compared with chewed prasugrel, which led to higher active metabolite concentration but not greater IPA compared with integral prasugrel. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02978040; URL: https://www.clinicaltrialsregister.eu; EudraCT 2017-001065-24.

Pharmacokinetics, mass balance, and metabolism of [14C]vicagrel, a novel irreversible P2Y12 inhibitor in humans.

Vicagrel, a novel irreversible P2Y12 receptor inhibitor, is undergoing phase III trials for the treatment of acute coronary syndromes in China. In this study, we evaluated the pharmacokinetics, mass balance, and metabolism of vicagrel in six healthy male Chinese subjects after a single oral dose of 20 mg [14C]vicagrel (120 µCi). Vicagrel absorption was fast (Tmax = 0.625 h), and the mean t1/2 of vicagrel-related components was ~38.0 h in both plasma and blood. The blood-to-plasma radioactivity AUCinf ratio was 0.55, suggesting preferential distribution of drug-related material in plasma. At 168 h after oral administration, the mean cumulative excreted radioactivity was 96.71% of the dose, including 68.03% in urine and 28.67% in feces. A total of 22 metabolites were identified, and the parent vicagrel was not detected in plasma, urine, or feces. The most important metabolic spot of vicagrel was on the thiophene ring. In plasma pretreated with the derivatization reagent, M9-2, which is a methylated metabolite after thiophene ring opening, was the predominant drug-related component, accounting for 39.43% of the radioactivity in pooled AUC0-8 h plasma. M4, a mono-oxidation metabolite upon ring-opening, was the most abundant metabolite in urine, accounting for 16.25% of the dose, followed by M3-1, accounting for 12.59% of the dose. By comparison, M21 was the major metabolite in feces, accounting for 6.81% of the dose. Overall, renal elimination plays a crucial role in vicagrel disposition, and the thiophene ring is the predominant metabolic site.

Impact of low-dose prasugrel on platelet reactivity and cardiac dysfunction in acute coronary syndrome patients requiring primary drug-eluting stent implantation: A randomized comparative study.

OBJECTIVE: The aim of this study was to compare how prasugrel and clopidogrel affect platelet aggregation reactivity, cardiac enzyme release, cardiac remodeling, and the formation of in-stent thrombi after primary percutaneous coronary intervention (PCI). BACKGROUND: The advantages of using prasugrel over clopidogrel in cardiac injury following acute coronary syndrome (ACS) remain unclear. METHODS: A total of 78 ACS patients were randomly allocated into clopidogrel (300 mg loading/75 mg maintenance) or prasugrel (20 mg loading/3.75 mg maintenance) treatment groups, followed by undergoing primary PCI. Platelet reactivity and cardiac enzymes were measured before and after primary PCI. Moreover, cardiac function was measured by ultrasound echocardiography and coronary angioscopic observation was after primary PCI up to 8 months later. RESULTS: Antiplatelet reactivity in the prasugrel treatment group reached optimal levels (P2Y12 reaction units [PRU] less than 262) immediately after the administration and was maintained even at 8 months, independently of the CYP2C19 genotype. Prasugrel treatment significantly suppressed creatine kinase elevation compared to clopidogrel treatment (median value 404 IU/L to 726 IU/L vs. 189 IU/L to 1,736 IU/L, p = 0.018 for maximum values) and reduced left ventricular mass (217.2-168.8 g in prasugrel, p = 0.045; 196.9-176.4 g in clopidogrel, p = 0.061). There were no significant differences in the incidence of in-stent attached thrombi between the two groups. CONCLUSIONS: Compared to clopidogrel, prasugrel produced a stable platelet aggregation inhibitory effect in patients with ACS regardless of CYP2C19 genotype, reduced cardiac enzyme release, and prevented cardiac remodeling after ACS.

Potential and Limitations of the New P2Y12 Inhibitor, Cangrelor, in Preventing Heparin-Induced Platelet Aggregation During Cardiac Surgery: An In Vitro Study.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) can put cardiac surgery patients at a high risk of lethal complications. If anti-PF4/heparin antibodies (anti-PF4/Hep Abs) are present, 2 strategies exist to prevent intraoperative aggregation during bypass surgery: first, using an alternative anticoagulant, and second, using heparin combined with an antiaggregant. The new P2Y12 inhibitor, cangrelor, could be an attractive candidate for the latter strategy; several authors have reported its successful use. The present in vitro study evaluated cangrelor's ability to inhibit heparin-induced platelet aggregation in the presence of anti-PF4/Hep Abs. METHODS: Platelet-poor plasma (PPP) from 30 patients with functional anti-PF4/Hep Abs was mixed with platelet-rich plasma (PRP) from 5 healthy donors.Light transmission aggregometry was used to measure platelet aggregation after adding 0.5 IU·mL of heparin (HIT) to the plasma, and this was compared with samples spiked with normal saline (control) and samples spiked with cangrelor 500 ng·mL and heparin 0.5 IU·mL (treatment). Friedman test with post hoc Dunn-Bonferroni test was used for between-group comparisons. RESULTS: Heparin 0.5 IU·mL triggered aggregation in 22 of 44 PPP-PRP mixtures, with a median aggregation of 86% (interquartile range [IQR], 69-91). The median aggregation of these 22 positive samples' respective control tests was 22% (IQR, 16-30) (P < .001). Median aggregation in the cangrelor-treated samples was 29% (IQR, 19-54) and significantly lower than the HIT samples (P < .001). Cangrelor inhibited heparin-induced aggregation by a median of 91% (IQR, 52-100). Cangrelor only reduced heparin-induced aggregation by >95% in 10 of the 22 positive samples (45%). Cangrelor inhibited heparin-induced aggregation by <50% in 5 of the 22 positive samples (22%) and by <10% in 3 samples (14%). CONCLUSIONS: This in vitro study found that cangrelor was an unreliable inhibitor of heparin-induced aggregation in the presence of anti-PF4/Hep Abs. We conclude that cangrelor should not be used as a standard antiaggregant for cardiac patients affected by HIT during surgery. Unless cangrelor's efficacy in a particular patient has been confirmed in a presurgery aggregation test, other strategies should be chosen.

Population pharmacokinetics and pharmacodynamics of ticagrelor and AR-C124910XX in Chinese healthy male subjects.

BACKGROUND: Ticagrelor, the first reversible P2Y12 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.

Pharmacokinetics and pharmacodynamics of ticagrelor in subjects on hemodialysis and subjects with normal renal function.

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 (P2Y12 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 (Cmax) and area under the plasma concentration curve from time zero to infinity (AUC0-∞) 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. Cmax and AUC0-∞ 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.

Ticagrelor pharmacokinetics and pharmacodynamics in patients with NSTEMI after a 180-mg loading dose.

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 (Tmax). Clinical trial registration identifier number: NCT02292277. None of the pharmacokinetic variables differed significantly between the groups, including the Tmax 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.

Population pharmacokinetics of ticagrelor and AR-C124910XX in patients with prior myocardial infarction
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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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Comparative pharmacodynamic effects of two clopidogrel formulations under steady-state conditions in healthy Thai volunteers
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OBJECTIVE: Clopidogrel is a commonly used antiplatelet aggregation agent. Compared with the reference clopidogrel product, most commercially available generic clopidogrel products contain different crystalline forms of clopidogrel. This study was aimed to compare the pharmacodynamics of a commonly used generic clopidogrel product in Thailand with the reference clopidogrel product under steady state conditions. METHODS: A multiple-dose, randomized 2-way crossover study was conducted in 32 healthy male Thai volunteers. The subjects were assigned to receive 75 mg once daily of the test or the reference product for 7 days with a 2-week wash out period. Blood samples were collected on days 1, 5, 6, and 7 prior to drug administration and at 1, 2, 3, 4, 8, 12, and 24 hours after the last dose administered. The antiplatelet aggregation effects of clopidogrel were determined by using two different ex-vivo platelet aggregation tests including the whole blood impedance assay (WBA) and the VerifyNow® P2Y12 assay. Both pharmacodynamic parameters, the maximal antiplatelet effect (Emax) and the areas under the antiplatelet effect-time curve (AUEC0-24h), were calculated. RESULTS: Neither the mean values of Emax (90.70 ± 15.15 vs. 89.50 ± 10.71% inhibition) nor of AUEC0-24h (1,892.84 ± 657.22 vs. 1,853.58 ± 673.95% inhibition × h) under steady-state conditions obtained using the WBA method of these two clopidogrel products were significantly different. The results obtained using the VerifyNow® P2Y12 assay were consistent with those of the WBA assay. CONCLUSION: This study clearly demonstrated that ex-vivo antiplatelet aggregation effect under steady-state conditions of the test product was not significantly different from the reference product.
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Self-Powered Microfluidic Device for Rapid Assay of Antiplatelet Drugs.

We report the development of a microfluidic device for the rapid assay in whole blood of interfacial platelet-protein interactions indicative of the efficacy of antiplatelet drugs, for example, aspirin and Plavix, two of the world's most widely used drugs, in patients with cardiovascular disease (CVD). Because platelet adhesion to surface-confined protein matrices is an interfacial phenomenon modulated by fluid shear rates at the blood/protein interface, and because such binding is a better indicator of platelet function than platelet self-aggregation, we designed, fabricated, and characterized the performance of a family of disposable, self-powered microfluidic chips with well-defined flow and interfacial shear rates suitable for small blood volumes (≤200 µL). This work demonstrates that accurate quantification of cell adhesion to protein matrices, an important interfacial biological phenomenon, can be used as a powerful diagnostic tool in those with CVD, the world's leading cause of death. To enable such measurements, we developed a simple technique to fabricate single-use self-powered chips incorporating shear control (SpearChips). These parallel-plate flow devices integrate on-chip vacuum-driven blood flow, using a predegassed elastomer component to obviate active pumping, with microcontact-printed arrays of 6-µm-diameter fluorescently labeled fibrinogen dots on a cyclic olefin polymer base plate as a means to quantitatively count platelet-protein binding events. The use of SpearChips to assess in whole blood samples the effects of GPIIb/IIIa and P2Y12 inhibitors, two important classes of "antiplatelet" drugs, is reported.

Comparison of VerifyNow P2Y12 and thrombelastography for assessing clopidogrel response in stroke patients in China.

Poor response to clopidogrel is often associated with recurrent ischemic events, and reliable platelet function tests are needed to identify clopidogrel low response (CLR). The aim of the study was to compare the consistency of VerifyNow P2Y12 and thrombelastography (TEG) in acute ischemic stroke patients treated with clopidogrel. Patients hospitalized in Changhai Hospital from August 2012 to September 2013 and assigned to treatment with a daily 75-mg dose of clopidogrel. The blood samples were taken on the 5-7th day to assess the capability of VerifyNow P2Y12 and TEG for evaluation of clopidogrel response, and all instrument parameters were used to perform correlation analysis. Patients with CLR were detected by using the methods and criteria published earlier (PRU ≥ 230 assayed by VerifyNow P2Y12 or TEG-Inhib% ≤30 % measured by TEG). Totally 58 patients were enrolled for the study and there were wide varieties in parameters of VerifyNow P2Y12 and TEG. Results showed a total of 17 and 9 patients, respectively, identified as CLR assessed by VerifyNow P2Y12 and TEG, but only three patients were detected to be clopidogrel low responders with both tests. The kappa consistency analysis showed poor consistency between VerifyNow P2Y12 and TEG results in terms of CLR (Kappa = -0.0349, p = 0.7730). Linear regression also demonstrated poor correlation between VerifyNow-PRU/VerifyNow-Inhib% and TEG-Inhib% (p = 0.07901 and p = 0.3788, respectively). Our study demonstrated that there was poor correlation between VerifyNow P2Y12 and TEG results, and VerifyNow P2Y12 showed a larger proportion of CLR than TEG.

Effect of genetic variations on ticagrelor plasma levels and clinical outcomes.

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.

Impact of non-inhibited platelet supplementation on platelet reactivity in patients treated with prasugrel or ticagrelor for an acute coronary syndrome: An ex vivo study.

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.

Pharmacokinetics, pharmacodynamics, and tolerability of single and multiple doses of ticagrelor in Japanese and Caucasian volunteers.

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.

A pharmacokinetic interaction study of ticagrelor and digoxin in healthy volunteers.

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.

Effect of rifampicin on the pharmacokinetics and pharmacodynamics of ticagrelor in healthy subjects.

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.

Effects of cangrelor in coronary artery disease patients with and without diabetes mellitus: an in vitro pharmacodynamic investigation.

Platelets from patients with diabetes mellitus (DM) are hyper-reactive and whether cangrelor, a potent intravenous P2Y(12) receptor blocker, has differential pharmacodynamic (PD) effects according DM status is unknown. The aim of this investigation was to evaluate the in vitro PD effects of cangrelor in coronary artery disease (CAD) patients with and without DM. This prospective study enrolled 120 clopidogrel-naïve patients with CAD on aspirin therapy. PD assessments using cangrelor (500 nmol/l) in vitro included vasodilator-stimulated phosphoprotein assay to obtain the P2Y(12) reactivity index (PRI), and multiple electrode aggregometry (MEA). In a 20 patients subgroup, dose-dependent response was assessed following exposure to escalating concentrations (baseline, 5, 50, 500 and 5,000 nmol/l); thrombin generation processes were evaluated by thromboelastography (TEG). PD data were evaluable in 103 patients. No differences in baseline PD parameters were observed in DM (n = 48) and non-DM (n = 45) subjects. Cangrelor reduced PRI values irrespective of DM status (p < 0.0001), yielding no difference in patients with and without DM (16.1 ± 12.3 vs. 16.8 ± 11.3; p = 0.346). All MEA values were significantly reduced, although this was of greater magnitude with purinergic compared to non-purinergic agonists. A trend analysis showed a dose-dependent effect on platelet inhibition, with no interaction due to DM status, whereas no significant dose-dependent effect was observed for TEG-derived parameters. Therefore, in vitro cangrelor provides potent and dose-dependent blockade of the platelet P2Y(12) receptor, with no differential effect in DM and non-DM patients. In addition, in vitro cangrelor exerts moderate inhibitory effects on non-purinergic platelet signaling pathways, without modulating platelet-derived thrombin generation processes.

Disposition and metabolism of ticagrelor, a novel P2Y12 receptor antagonist, in mice, rats, and marmosets.

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.