Platelets
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Previous laboratory and clinical data have shown evidence for the concept of rebalanced hemostasis in liver disease. We evaluate whether this concept of rebalanced hemostasis can be applied in patients with idiopathic thrombocytopenic purpura (ITP). Twenty patients with ITP (platelet count < 100 × 10(9) /l) who visited our hospital were enrolled. ⋯ We found that the vWF antigen level was elevated and the TEG profiles were better in older ITP patients with longer disease statuses. Patients with ITP appeared to achieve a rebalance hemostasis through an elevation of their plasma vWF antigen levels and hemostatic changes that promote thrombosis. Measuring the vWF antigen levels and performing TEG analysis can help determine the treatment strategy in ITP patients.
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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. ⋯ 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.
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Platelets of patients with sickle cell disease (SCD) show evidence of mild activation in the non-crisis steady state and greater activation during vaso-occlusive crises (VOC). Prasugrel, a potent inhibitor of ADP-mediated platelet activation and aggregation, may be useful in attenuating VOC. We compared platelet responses to ADP stimulation in patients with SCD and healthy subjects before and after treatment with prasugrel. ⋯ Furthermore, prasugrel decreases ex vivo ADP-stimulated platelet aggregation with monocytes and neutrophils as measured by the monocyte-platelet and neutrophil-platelet aggregate MFI. This implies that in the presence of prasugrel, fewer platelets adhere to monocytes and neutrophils, which may result in reducing cell-platelet aggregate size. Therefore, reduced platelet reactivity and decreased size of leukocyte-platelet aggregates suggest additional mechanisms by which prasugrel may provide benefit to patients with SCD and support further investigation of possible therapeutic benefits of prasugrel in this population.
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The novel antiplatelet agent ticagrelor has been demonstrated to exert a faster and more powerful inhibition of platelet aggregation in comparison to clopidogrel in coronary artery disease patients. However, a ticagrelor dose of 90 mg twice daily might not be suitable for patients of East Asian ethnicity, and has not been fully investigated. The aim of this study was to assess the effects of low loading doses (LD, 90 mg) and maintenance doses (MD, 90 mg daily) of ticagrelor in comparison to clopidogrel (600 mg LD, 75 mg daily MD) in healthy Korean volunteers. ⋯ The low loading and maintenance doses of ticagrelor (90 mg LD, 90 mg daily MD) cause a more rapid and potent inhibition of platelet function when compared to clopidogrel (600 mg LD and 75 mg MD). Additionally, at the lowest value of platelet inhibition strength, oral once-daily administration of ticagrelor was no less efficacious than clopidogrel at the 24- and 120-hour time points. Due to a large diurnal variation occurring with a single daily dose, a lower dose twice-daily could be a better option for patients of East Asian ethnicity.