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Although acid suppressants are needed to attenuate gastrointestinal bleeding (GIB) after percutaneous coronary intervention (PCI), pharmacodynamic interaction between clopidogrel and proton pump inhibitor (PPI) can increase the risk of high platelet reactivity (HPR). We sought to evaluate serial changes of platelet measures and influence of rabeprazole on platelet measures. After 600-mg clopidogrel loading for elective PCI, clopidogrel-sensitive patients were recruited and randomly assigned to add rabeprazole of daily 20 mg (n = 40) or famotidine of daily 40 mg (n = 40). Platelet measures were performed with light transmittance aggregometry and VASP-P assay. Primary endpoint was 5 μM ADP-induced platelet aggregation (PA) at 30-day follow-up. HPR was defined as 5 μM ADP-induced PA > 46%. Baseline platelet measures did not differ significantly between the groups. The 30-day level of 5 μM ADP-induced PA was similar between the famotidine vs. rabeprazole group (30.0 ± 16.4% vs. 30.2 ± 13.9%, P = .956). In addition, other platelet measures were comparable between the groups. At 30-day follow-up, the incidence of HPR was similar between the famotidine and rabeprazole groups (20.5% vs. 15.4%; P = .555). In conclusion, adjunctive use of rabeprazole showed the similar antiplatelet effect even in clopidogrel-sensitive patients compared with adjunctive famotidine, which may support the similar effect of rabeprazole and famotidine on the antiplatelet effect of dual antiplatelet therapy with clopidogrel plus aspirin.

Amlodipine has a potential to reduce clopidogrel bioactivation through the cytochrome P450 3A4 enzyme in vivo, but the clinical impact of this interaction remains controversial. This randomized, open-label, two-period, crossover study was performed to evaluate the influence of amlodipine on the haemostatic profiles of high-risk patients during clopidogrel treatment. We recruited 40 Asian patients (Male/Female: n  = 36/4) receiving clopidogrel (75 mg/day), aspirin (100 mg/day) and rosuvastatin for at least 6 months following percutaneous coronary intervention. Patients were randomly assigned to receive either 5 mg daily amlodipine or not for 2 weeks, and then were crossed over to the other treatment for 2 weeks. Haemostatic measurements were conducted with the VerifyNow assay and thromboelastography (TEG). Primary endpoint was P2Y12 Reaction Units (PRU) during on- versus off-amlodipine treatment. The on-amlodipine strategy showed higher level of PRU compared with the off-amlodipine strategy (176.8 ± 75.4 vs. 150.7 ± 65.5 PRU; ∆mean: 26.1 PRU; ∆95% confidence interval [CI]: 4.5-47.7 PRU; p  = 0.019). Platelet-fibrin clot strength measured by TEG was lower during on- versus off-amlodipine treatment (7,712 ± 1,889 vs. 8,559 ± 2,174 dyne/cm 2 ; ∆mean: -847 dyne/cm 2 ; ∆95% CI: -1,632 to -62 dyne/cm 2 ; p  = 0.035). After amlodipine discontinuation, 27 patients (67.5%) showed a decrease in PRU, which was associated with 'PRU ≥ 160 on-amlodipine' in multivariate analysis (odds ratio: 62.014; 95% CI: 2.302-1670.328; p  = 0.014). In conclusion, amlodipine increases platelet reactivity and decreases platelet-fibrin clot strength during clopidogrel treatment. In addition, the effect of amlodipine discontinuation on clopidogrel responsiveness is associated with on-amlodipine platelet reactivity., Competing Interests: Dr. Jeong has received honoraria for lectures from AstraZeneca, Sanofi-Aventis, Daiichi Sankyo/Lilly, Haemonetics, Otsuka, Han-mi Pharmaceuticals and Yuhan Pharmaceuticals; and research grants or support from AstraZeneca, Korean Society of Interventional Cardiology, Han-mi Pharmaceuticals, Daewoong Pharmaceuticals and Haemonetics. Dr. Gurbel reports serving as a consultant/receiving honoraria from Bayer, Merck, Janssen, Medicure and US WorldMeds and receiving grants from the National Institutes of Health, Janssen, Merck, Amgen, Medicure, Bayer, Instrumentation Labs, Haemonetics and Idorsia. Dr. Gurbel also has patents in the field of platelet function testing. The other authors report no conflicts of interest., (Georg Thieme Verlag KG Stuttgart · New York.)

Dual antiplatelet therapy (DAPT) with clopidogrel and aspirin is a widely prescribed regimen to prevent ischemic events in patients undergoing percutaneous coronary intervention (PCI). A fixed-dose combination (FDC) capsule (HCP0911) has been developed to provide dosing convenience and improve adherence. We compared the antiplatelet effects of single daily dose HCP0911 with separate treatment with daily 75 mg clopidogrel plus 100 mg aspirin. This was a randomized, open-label, two-period, crossover, non-inferiority study conducted in stented patients who had been treated for at least 6 months with clopidogrel and aspirin. Thirty patients were randomly assigned to receive either daily 75 mg clopidogrel plus 100 mg aspirin treatment or HCP0911 for 2 weeks and then were crossed over to the other treatment for 2 weeks. Pharmacodynamic effects were measured with VerifyNow, light transmittance aggregometry (LTA), and thromboelastography (TEG®). The primary endpoint was P2Y12 Reaction Units (PRU) measured by VerifyNow. PRUs during treatment with HCP0911 were not inferior to those during separate treatment (202 ± 52 vs. 207 ± 60 PRU; mean difference, −5 PRU; 90% confidence interval of difference, −23 to 13 PRU; P for non-inferiority = 0.015 for predetermined limit). "BASE" and Aspirin Reaction Units by VerifyNow did not differ between the two treatments. During each treatment, there were no differences in maximal and final platelet aggregations by LTA (all P values ≥0.822) and TEG® measurements. In conclusion, in stented patients, the antiplatelet effect of a fixed-dose clopidogrel–aspirin combination, HCP0911, was not inferior to separate administration of clopidogrel and aspirin. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the effect of clopidogrel vs. aspirin monotherapy on vascular function and hemostatic measurement. Background: Monotherapy with P2Y12 receptor inhibitor vs. aspirin can be a useful alterative to optimize clinical efficacy and safety in high-risk patients with coronary artery disease (CAD). Methods: We performed a randomized, open-label, two-period crossover study in stented patients receiving at least 6-month of dual antiplatelet therapy (DAPT). Thirty CAD patients with moderate-to-high ischemic risk were randomly assigned to receive either 75 mg of clopidogrel or 100 mg of aspirin daily for 4 weeks, and were crossed over to the other strategy for 4 weeks. Vascular function was evaluated with reactive hyperemia-peripheral arterial tonometry (RH-PAT) and brachial-ankle pulse wave velocity (baPWV). Hemostatic profiles were measured with VerifyNow and thromboelastography (TEG). The primary endpoint was the reactive hyperemia index (RHI) during clopidogrel or aspirin monotherapy. Results: Clopidogrel vs. aspirin monotherapy was associated with better endothelial function (RHI: 2.11 ± 0.77% vs. 1.87 ± 0.72%, p = 0.045), lower platelet reactivity (130 ± 64 vs. 214 ± 50 P2Y12 reaction unit [PRU], p < 0.001) and prolonged reaction time (TEG R: 5.5 ± 1.2 vs. 5.1 ± 1.1 min, p = 0.037). In multivariate analysis, normal endothelial function (RHI ≥ 2.1) was significantly associated with clot kinetics (TEG angle ≤ 68 degree) and 'PRU ≤ 132'. 'PRU ≤ 132' was achieved in 46.2% vs. 3.8% during clopidogrel administration vs. aspirin monotherapy (odds ratio 21.4, 95% confidence interval 2.7 to 170.1, p < 0.001). Conclusions: In CAD patients, clopidogrel vs. aspirin monotherapy was associated with better endothelial function, greater platelet inhibition and lower coagulation activity, suggesting pleiotropic effects of clopidogrel on endothelial function and hemostatic profiles. [ABSTRACT FROM AUTHOR]