Kathleen Butler

Randomized Double-Blind Assessment of the ONSET and OFFSET of the Antiplatelet Effects of Ticagrelor Versus Clopidogrel in Patients With Stable Coronary Artery Disease The ONSET/OFFSET Study

Background— Ticagrelor is the first reversibly binding oral P2Y12 receptor antagonist. This is the first study to compare the onset and offset of platelet inhibition (IPA) with ticagrelor using the PLATO (PLATelet inhibition and patient Outcomes) trial loading dose (180 mg) with a high loading dose (600 mg) of clopidogrel. Methods and Results— In a multicenter, randomized, double-blind study, 123 patients with stable coronary artery disease who were taking aspirin therapy (75 to 100 mg/d) received ticagrelor (180-mg load, 90-mg BID maintenance dose [n=57]), clopidogrel (600-mg load, 75-mg/d maintenance dose [n=54]), or placebo (n=12) for 6 weeks. Greater IPA (20 &mgr;mol/L ADP, final extent) occurred with ticagrelor than with clopidogrel at 0.5, 1, 2, 4, 8, and 24 hours after loading and at 6 weeks (P<0.0001 for all); by 2 hours after loading, a greater proportion of patients achieved >50% IPA (98% versus 31%, P<0.0001) and >70% IPA (90% versus 16%, P<0.0001) in the ticagrelor group than in the clopidogrel group, respectively. A faster offset occurred with ticagrelor than with clopidogrel (4-to-72–hour slope [% IPA/h] −1.04 versus −0.48, P<0.0001). At 24 hours after the last dose, mean IPA was 58% for ticagrelor versus 52% for clopidogrel (P=NS). IPA for ticagrelor on day 3 after the last dose was comparable to clopidogrel at day 5; IPA on day 5 for ticagrelor was similar to clopidogrel on day 7 and did not differ from placebo (P=NS). Conclusions— Ticagrelor achieved more rapid and greater platelet inhibition than high-loading-dose clopidogrel; this was sustained during the maintenance phase and was faster in offset after drug discontinuation. Clinical Trial Registration Information— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00528411.

Randomized Double-Blind Assessment of the ONSET and OFFSET of the Antiplatelet Effects of Ticagrelor Versus Clopidogrel in Patients With Stable Coronary Artery Disease Randomized Double-Blind Assessment of the ONSET and OFFSET of the Antiplatelet Effects of Ticagrelor Versus Clopidogrel in Patients With Stable Cornonary Disease: The ONSET/OFFSET Study

Background— Ticagrelor is the first reversibly binding oral P2Y12 receptor antagonist. This is the first study to compare the onset and offset of platelet inhibition (IPA) with ticagrelor using the PLATO (PLATelet inhibition and patient Outcomes) trial loading dose (180 mg) with a high loading dose (600 mg) of clopidogrel. Methods and Results— In a multicenter, randomized, double-blind study, 123 patients with stable coronary artery disease who were taking aspirin therapy (75 to 100 mg/d) received ticagrelor (180-mg load, 90-mg BID maintenance dose [n=57]), clopidogrel (600-mg load, 75-mg/d maintenance dose [n=54]), or placebo (n=12) for 6 weeks. Greater IPA (20 &mgr;mol/L ADP, final extent) occurred with ticagrelor than with clopidogrel at 0.5, 1, 2, 4, 8, and 24 hours after loading and at 6 weeks (P<0.0001 for all); by 2 hours after loading, a greater proportion of patients achieved >50% IPA (98% versus 31%, P<0.0001) and >70% IPA (90% versus 16%, P<0.0001) in the ticagrelor group than in the clopidogrel group, respectively. A faster offset occurred with ticagrelor than with clopidogrel (4-to-72–hour slope [% IPA/h] −1.04 versus −0.48, P<0.0001). At 24 hours after the last dose, mean IPA was 58% for ticagrelor versus 52% for clopidogrel (P=NS). IPA for ticagrelor on day 3 after the last dose was comparable to clopidogrel at day 5; IPA on day 5 for ticagrelor was similar to clopidogrel on day 7 and did not differ from placebo (P=NS). Conclusions— Ticagrelor achieved more rapid and greater platelet inhibition than high-loading-dose clopidogrel; this was sustained during the maintenance phase and was faster in offset after drug discontinuation. Clinical Trial Registration Information— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00528411.

Response to Ticagrelor in Clopidogrel Nonresponders and Responders and Effect of Switching Therapies. The RESPOND Study

Background— The antiplatelet effects of the Platelet Inhibition and Patient Outcomes (PLATO) trial dose of ticagrelor in patients nonresponsive to clopidogrel and after they switch agents are unknown. Methods and Results— Patients with stable coronary artery disease on aspirin therapy received a 300-mg clopidogrel load; nonresponders were identified by light transmittance aggregometry. In a 2-way crossover design, nonresponders (n=41) and responders (n=57) randomly received clopidogrel (600 mg/75 mg once daily) or ticagrelor (180 mg/90 mg twice daily) for 14 days during period 1. In period 2, all nonresponders switched treatment; half of the responders continued the same treatment, whereas the others switched treatment. Inhibition of platelet aggregation was higher in nonresponders treated with ticagrelor compared with clopidogrel (P<0.05). Treatment with ticagrelor among nonresponders resulted in a >10%, >30%, and >50% decrease in platelet aggregation from baseline in 100%, 75%, and 13% of patients, respectively. Platelet aggregation fell from 59±9% to 35±11% in patients switched from clopidogrel to ticagrelor and increased from 36±14% to 56±9% in patients switched from ticagrelor to clopidogrel (P<0.0001 for both). Platelet reactivity was below the cut points previously associated with ischemic risk measured by light transmittance aggregometry, VerifyNow P2Y12 assay, and vasodilator-stimulated phosphoprotein phosphorylation in 98% to 100% of patients after ticagrelor therapy versus 44% to 76% of patients after clopidogrel therapy. Conclusions— Ticagrelor therapy overcomes nonresponsiveness to clopidogrel, and its antiplatelet effect is the same in responders and nonresponders. Nearly all clopidogrel nonresponders and responders treated with ticagrelor will have platelet reactivity below the cut points associated with ischemic risk. Clinical Trial Registration— http://www.clinicaltrials.gov. Unique Identifier: NCT00642811.

Incidence of dyspnea and assessment of cardiac and pulmonary function in patients with stable coronary artery disease receiving ticagrelor, clopidogrel, or placebo in the ONSET/OFFSET study

OBJECTIVES We prospectively assessed cardiac and pulmonary function in patients with stable coronary artery disease (CAD) treated with ticagrelor, clopidogrel, or placebo in the ONSET/OFFSET (A Multi-Centre Randomised, Double-Blind, Double-Dummy Parallel Group Study of the Onset and Offset of Antiplatelet Effects of AZD6140 Compared With Clopidogrel and Placebo With Aspirin as Background Therapy in Patients With Stable Coronary Artery Disease) study. BACKGROUND Ticagrelor reduces cardiovascular events more effectively than clopidogrel in patients with acute coronary syndromes. Dyspnea develops in some patients treated with ticagrelor, and it is not known whether this is associated with changes in cardiac or pulmonary function. METHODS In all, 123 stable aspirin-treated CAD patients randomly received either ticagrelor (180 mg load, then 90 mg twice daily; n=57), clopidogrel (600 mg load, then 75 mg daily; n=54), or placebo (n=12) for 6 weeks in a double-blind, double-dummy design. Electrocardiography, echocardiography, serum N-terminal pro-brain natriuretic peptide, and pulmonary function tests were performed before (baseline) and 6 weeks after drug administration and/or after development of dyspnea. RESULTS After drug administration, dyspnea was reported by 38.6%, 9.3%, and 8.3% of patients in the ticagrelor, clopidogrel, and placebo groups, respectively (p<0.001). Most instances were mild and/or lasted<24 h, although 3 patients discontinued ticagrelor because of dyspnea. Eight of 22 and 17 of 22 ticagrelor-treated patients experiencing dyspnea did so within 24 h and 1 week, respectively, after drug administration. In all treatment groups, and in ticagrelor-treated patients with dyspnea, there were no significant changes between baseline and 6 weeks in any of the cardiac or pulmonary function parameters. CONCLUSIONS Dyspnea is commonly associated with ticagrelor therapy, but was not associated in this study with any adverse change in cardiac or pulmonary function. (A Multi-Centre Randomised, Double-Blind, Double-Dummy Parallel Group Study of the Onset and Offset of Antiplatelet Effects of AZD6140 Compared With Clopidogrel and Placebo With Aspirin as Background Therapy in Patients With Stable Coronary Artery Disease [ONSET/OFFSET]; NCT00528411).

First Analysis of the Relation Between CYP2C19 Genotype and Pharmacodynamics in Patients Treated With Ticagrelor Versus Clopidogrel The ONSET/OFFSET and RESPOND Genotype Studies

Background—The influence of cytochrome P450 (CYP) 2C19 genotype on platelet function in patients treated with ticagrelor versus clopidogrel is unknown. Methods and Results—CYP2C19 (*1, *2, *3, *4, *5, *6, *7, *8, *17) genotyping was performed in patients with coronary artery disease treated with ticagrelor (180-mg load, 90 mg BID) (n=92) or clopidogrel (600-mg load, 75 mg/d) (n=82). All patients received 75 to 100 mg/d aspirin. Platelet function was measured by aggregometry, VerifyNow P2Y12 assay, and vasodilator-stimulated phosphoprotein-phosphorylation assay at predose, 8 hours postloading, and maintenance. In each treatment group, patients were categorized according to 2C19 genotype carrier status (loss-of-function, gain-of-function) and metabolizer status. Kruskal-Wallis test was used to compare platelet function among these categories for each treatment, and Wilcoxon rank sum test was used to compare platelet function between the clopidogrel and ticagrelor groups for each category. There was no statistically significant influence of genotype on platelet function during aspirin therapy alone. Ticagrelor exhibited lower platelet reactivity than clopidogrel by all assays irrespective of 2C19 genotype or metabolizer status (P<0.01). Loss-of-function carriers had greater platelet reactivity during clopidogrel therapy. The influence of genotype on platelet reactivity was greatest during clopidogrel maintenance and best demonstrated by the VerifyNow P2Y12 assay. Conclusions—This report is the first to demonstrate the superior pharmacodynamic effect of ticagrelor compared with clopidogrel irrespective of CYP2C19 genotype. Whereas CYP2C19 genotype influenced the antiplatelet effect of clopidogrel, there was no effect of CYP2C19 genotype during ticagrelor therapy. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifiers: NCT00642811 and NCT00528411.

Pharmacokinetics, pharmacodynamics, safety and tolerability of multiple ascending doses of ticagrelor in healthy volunteers.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT The antiplatelet agent clopidogrel is currently the recommended treatment for acute coronary syndrome (ACS). Inhibition of platelet aggregation (IPA) with clopidogrel is insufficient, which increases the risk for recurrent ischaemic events. Therefore, there is a need for antiplatelet agents with improved IPA. Ticagrelor (AZD6140) is a new antiplatelet agent in clinical development for reduction of thrombotic events in patients with ACS. WHAT THIS STUDY ADDS This study assesses the optimal dosing schedule for ticagrelor in healthy volunteers and compares the degree of IPA with clopidogrel. Our findings illustrate that the pharmacokinetics of ticagrelor are predictable and are associated with consistent inhibition of platelet activity. IPA with ticagrelor was greater and better sustained at high levels with twice daily ticagrelor than once daily regimens. AIM To determine the pharmacokinetics, pharmacodynamics, safety and tolerability of multiple oral doses of ticagrelor, a P2Y(12) receptor antagonist, in healthy volunteers. METHODS This was a randomized, single-blind, placebo-controlled, ascending dose study. Thirty-two subjects received ticagrelor 50-600 mg once daily or 50-300 mg twice daily or placebo for 5 days at three dose levels in two parallel groups. Another group of 16 subjects received a clopidogrel 300 mg loading dose then 75 mg day(-1), or placebo for 14 days. RESULTS Ticagrelor was absorbed with median t(max) 1.5-3 h, exhibiting predictable pharmacokinetics over the 50-600 mg dose range. Mean C(max) and AUC for ticagrelor and its main metabolite, AR-C124910XX, increased approximately dose-proportionately (approximately 2.2- to 2.4-fold with a twofold dose increase) over the dose range. Inhibition of platelet aggregation (IPA) with ticagrelor was greater and better sustained at high levels with ticagrelor twice daily vs. once daily regimens. Throughout dosing, more consistent IPA was observed at doses > or = 300 mg once daily and > or = 100 mg twice daily compared with clopidogrel. Mean IPA with ticagrelor > or = 100 mg twice daily was greater and less variable (93-100%, range 65-100%) than with clopidogrel (77%, range 11-100%) at trough concentrations. No safety or tolerability issues were identified. CONCLUSIONS Multiple dosing provided predictable pharmacokinetics of ticagrelor and its metabolite over the dose range of 50-600 mg once daily and 50-300 mg twice daily with C(max) and AUC(0,t) increasing approximately dose-proportionally. Greater and more consistent IPA with ticagrelor at doses > or = 100 mg twice daily and > or = 300 mg once daily were observed than with clopidogrel. Ticagrelor at doses up to 600 mg day(-1) was well tolerated.

Pharmacokinetics and pharmacodynamics of ticagrelor in patients with stable coronary artery disease: results from the ONSET-OFFSET and RESPOND studies.

AbstractBackground and Objectives: Ticagrelor, the first reversibly binding oral P2Y12 receptor antagonist, improves outcomes in patients with acute coronary syndromes (ACS) compared with clopidogrel. In the ONSET-OFFSET study (parallel group trial) and the RESPOND study (crossover trial), the pharmacodynamic effects of ticagrelor were compared with clopidogrel in patients with coronary artery disease (CAD). We now report the pharmacokinetic analyses of ticagrelor, and the exposure-inhibition of platelet aggregation (IPA) relationships from these studies. Patients and Methods: Patients were treated with ticagrelor (180 mg loading dose, 90 mg twice daily maintenance dose) or clopidogrel (600 mg loading dose, 75 mg once daily maintenance dose) in addition to aspirin (acetylsalicylic acid) [75–100 mg once daily]. Ticagrelor administration was for 6 weeks in ONSET-OFFSET. In RESPOND, ticagrelor was given for 14 days before or after 2 weeks of clopidogrel in patients classified as clopidogrel responders or non-responders. Pharmacokinetics and IPA were evaluated following the loading and last maintenance doses. Exposure-IPA relationships were evaluated using a sigmoid maximum effect (Emax) model. Outcome Measures: The outcome measures were ticagrelor and AR-C124910XX (active metabolite) pharmacokinetics and exposure-IPA relationships in both trials, including the effect of prior clopidogrel exposure, and effects in clopidogrel responders and non-responders in RESPOND. Results: In ONSET-OFFSET, maximum (peak) plasma concentration (Cmax), time to Cmax (tmax) and area under the plasma concentration-time curve from time 0 to 8 hours (AUC8) for ticagrelor were 733 ng/mL, 2.0 hours and 4130 ng · h/mL, respectively; and for AR-C124910XX were 210 ng/mL, 2.1 hours and 1325 ng · h/mL, respectively. Emax estimates were IPA > 97%. Trough plasma ticagrelor (305 ng/mL) and AR-C124910XX (121 ng/mL) concentrations were 5.2 and 7.7 times higher than respective concentration producing 50% of maximum effect (EC50) estimates. In RESPOND, ticagrelor mean Cmax and AUC8 following 2-week dosing were comparable between clopidogrel responders (724 ng/mL and 3983 ng · h/mL, respectively) and non-responders (764 ng/mL and 3986 ng · h/mL, respectively). Pharmacokinetics of ticagrelor were unaffected by prior clopidogrel dosing. Emax estimates were IPA > 96% for both responders and non-responders. Trough plasma concentrations were sufficient to achieve high IPA. Conclusions: Ticagrelor pharmacokinetics in stable CAD patients were comparable to previous findings in stable atherosclerotic and ACS patients, and were not affected by prior clopidogrel exposure or clopidogrel responsiveness. Ticagrelor effectively inhibited platelet aggregation, and trough plasma concentrations of ticagrelor and AR-C124910XX were sufficient to result in high IPA in stable CAD patients.

Earlier recovery of platelet function after discontinuation of treatment with ticagrelor compared with clopidogrel in patients with high antiplatelet responses

Summary.  Background: The rate of recovery of platelet function after discontinuation of P2Y12 inhibitors depends on the reversibility of the antiplatelet effect and the extent of the on‐treatment response. P2Y12 inhibition increases the bleeding risk in patients requiring surgery. Objectives: To evaluate recovery of platelet function after discontinuation of ticagrelor vs. clopidogrel in stable coronary artery disease (CAD) patients with high levels of platelet inhibition (HPI) during the ONSET/OFFSET study. Methods: Patients received aspirin 75–100 mg per day and either ticagrelor 90 mg twice‐daily or clopidogrel 75 mg daily for 6 weeks. This subanalysis included patients with HPI after the last dose of maintenance therapy, defined as: inhibition of platelet aggregation (IPA) > 75% 4 h post‐dose (ADP 20 μm, final extent); < 120 P2Y12 reaction units 8 h post‐dose (VerifyNow P2Y12 assay); or platelet reactivity index < 50% 8 h post‐dose (VASP‐P assay). Results: IPA > 75% was observed in 39 out of 47 ticagrelor‐treated and 17 out of 44 clopidogrel‐treated patients. The rate of offset of IPA over 4–72 h was greater with ticagrelor (IPA %/hour slope: −1.11 vs. −0.67 for clopidogrel; P < 0.0001). Mean IPA was significantly lower with ticagrelor than clopidogrel between 48 and 168 h post‐dose (P < 0.01). Similar findings were observed with the other assays. The average time for IPA to decline from 30% to 10% was 50.8 h with ticagrelor vs. 110.4 h with clopidogrel. Conclusions: In patients with HPI, recovery of platelet function was more rapid after discontinuation of ticagrelor than clopidogrel leading to significantly greater platelet reactivity by 48 h after the last dose in the ticagrelor group.

Pharmacokinetics, Pharmacodynamics, and Safety of Ticagrelor in Volunteers With Severe Renal Impairment

Ticagrelor, a P2Y12 receptor antagonist, is approved in the European Union and the US for the prevention of thrombotic events in patients with acute coronary syndromes. Renal dysfunction potentially affects drug disposition. Ticagrelor pharmacokinetics, pharmacodynamics, and safety in renal impairment were assessed. A single 180‐mg ticagrelor dose was administered to volunteers with severe renal impairment (creatinine clearance [CrCL] < 30 mL/min) and normal renal function (CrCL ≥ 80 mL/min; n = 10/group). Severe renal impairment did not significantly affect ticagrelors pharmacokinetics, pharmacodynamics, or safety. Ticagrelor absorption and AR‐C124910XX (active metabolite) formation were rapid. In renally impaired volunteers, ticagrelor mean maximum concentration (Cmax) and area under the plasma concentration‐time curve from zero to infinity were 20% lower and for AR‐C124910XX was 17% higher versus normal volunteers. Ticagrelor systemic exposure was low in 3 volunteers (CrCL < 20 mL/min), but data were variable. Onset and offset of final‐extent inhibition of platelet aggregation were comparable in both groups. Inhibition of platelet aggregation parameters and profiles were similar between groups, indicating that platelet sensitivity to ticagrelor was not affected by severe renal impairment. Ticagrelor was well tolerated in both groups with few adverse events. No ticagrelor dose adjustment is required for renally impaired patients.

Pharmacokinetics and tolerability of single and multiple doses of ticagrelor in healthy Chinese subjects: an open-label, sequential, two-cohort, single-centre study.

AbstractBackground and Objectives: Ticagrelor (Brilinta™) is an antithrombotic agent that reversibly binds to P2Y12 receptors and inhibits adenosine diphosphate-induced platelet aggregation. Ticagrelor has undergone evaluation in the phase III PLATO trial, which enrolled 18 624 patients with acute coronary syndromes (ACS) from 43 countries, and 6% of patients were Asian. Subsequently, ticagrelor has now been approved in more than 40 countries for the prevention of atherothrombotic events in adult patients with ACS. Gene polymorphisms in drug-metabolizing enzymes may vary with ethnicity, and can alter drug exposure, potentially impacting drug efficacy and/or tolerability. The objectives of this study were to assess the pharmacokinetic parameters of ticagrelor and its active metabolite AR-C124910XX, and the safety and tolerability of ticagrelor in healthy Chinese subjects, following single and multiple oral doses of ticagrelor. Methods: This trial was an open-label, sequential, two-cohort, single-centre study investigating 90 mg and 180 mg doses of ticagrelor in healthy Chinese subjects. On day 1, 12 subjects received a single oral dose of ticagrelor 90 mg. Following a 2-day washout period, ticagrelor was administered twice daily (90 mg twice daily) on days 4–9 and as a single dose on day 10. After completion of this phase, additional subjects (n= 14) were recruited into the ticagrelor 180 mg group, and received ticagrelor 180 mg under the same dosing schedule. On days 1 and 10 of both dosing schedules, blood samples for pharmacokinetic analyses were collected for 72 hours. Results: Following single and multiple doses at both dose levels, ticagrelor was rapidly absorbed (median time [tmax] to reach maximum plasma concentration [Cmax] 2 hours) with a mean elimination half-life (t1/2) of 10.9–14.9 hours. AR-C124910XX was rapidly formed (median tmax 2.0–3.0 hours; mean t1/2 9.1–11.9 hours). Steady-state concentrations of ticagrelor and AR-C124910XX were rapidly established with both dosing regimens. Both parent and metabolite exhibited linear and predictable pharmacokinetics with single and multiple dosing as mean minimum plasma concentration (Cmin), Cmax and area under the plasma concentration-time curve from time zero to infinity (AUC∞) were approximately 2-fold higher with ticagrelor 180mg (e.g. multiple-dosing, geometric mean [% coefficient of variation]: Cmax 1973 [27] and AUC∞ 18 035 [46]) versus 90 mg (e.g. multiple dosing: Cmax 915 [32] and AUC∞ 7168 [35]) dosing regimens. Overall, ticagrelor was generally well tolerated in healthy Chinese subjects. Two subjects discontinued in the ticagrelor 90 mg group due to elevated serum levels of ALT and AST. Mild ticagrelor-associated adverse events were seen: bleeding events (90 mg: epistaxis n= 1; 180 mg: gingival bleeding n= 1) and dyspnoea (180 mg: n= 3). Conclusion: In healthy Chinese subjects, ticagrelor and AR-C124910XX pharmacokinetics were linear and predictable. Although ticagrelor and AR-C124910XX exposure at steady state were found to be slightly higher in Chinese subjects, these results were broadly similar to previous data in Caucasian subjects. Overall, ticagrelor was well tolerated in healthy Chinese subjects.