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Antiplatelet Effects (antiplatelet + effects)
Selected AbstractsBleeding risk with AZD6140, a reversible P2Y12 receptor antagonist, vs. clopidogrel in patients undergoing coronary artery bypass grafting in the DISPERSE2 trialINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 4 2009S. Husted Summary AZD6140, the first reversible oral P2Y12 receptor antagonist, exhibits greater and more consistent inhibition of platelet aggregation than the irreversible thienopyridine clopidogrel. As a result of its reversible effect, AZD6140 may pose less risk for bleeding when antiplatelet treatment cannot be stopped at least 5 days before coronary artery bypass graft (CABG) surgery or other invasive procedures. The Dose conflrmation Study assessing anti-Platelet Effects of AZD6140 vs. clopidogRel in NSTEMI (DISPERSE2) trial showed overall comparable bleeding rates with antiplatelet treatment with AZD6140 90 mg twice daily or 180 mg twice daily vs. clopidogrel 75 mg once daily in 984 patients with non-ST-elevation acute coronary syndromes. A post hoc exploratory analysis of bleeding outcomes in the subset of 84 patients undergoing CABG in DISPERSE2 suggests reduced risk for total bleeding (41% and 58% vs. 62%), all major bleeding (38% and 50% vs. 62%), and life-threatening bleeding (22% and 38% vs. 54%) with AZD6140 90 mg (n = 32) and 180 mg (n = 26) vs. clopidogrel (n = 26) respectively. Trends suggested that major bleeding rates were reduced with AZD6140 (combined groups) vs. clopidogrel when treatment was stopped , 5 days prior to surgery (39% vs. 63%, p = 0.15) but not when treatment was stopped > 5 days before surgery (50% vs. 60%). This observation is consistent with the reversible binding of AZD6140 to the P2Y12 receptor. Further prospective studies are planned to assess the relationship between this potential clinical benefit of AZD6140 and the reversibility of its antiplatelet effects. [source] Antiplatelet Effect of Marchantinquinone, Isolated from Reboulia hemisphaerica, in Rabbit Washed PlateletsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2000CHANG-HUI LIAO Platelet activation is involved in serious pathological situations, including atherosclerosis and restenosis. It is important to find efficient antiplatelet medicines to prevent fatal thrombous formation during the course of these diseases. Marchantinquinone, a natural compound isolated from Reboulia hemisphaerica, inhibited platelet aggregation and ATP release stimulated by thrombin (0.1 units mL,1), platelet-activating factor (PAF; 2 ng mL,1), collagen (10 ,g mL,1), arachidonic acid (100 ,m), or U46619 (1 ,m) in rabbit washed platelets. The IC50 values of marchantinquinone on the inhibition of platelet aggregation induced by these five agonists were 62.0 ± 9.0, 86.0 ± 7.8, 13.6 ± 4.7, 20.9 ± 3.1 and 13.4 ± 5.3 ,m, respectively. Marchantinquinone inhibited thromboxane B2 (TxB2) formation induced by thrombin, PAF or collagen. However, marchantinquinone did not inhibit TxB2 formation induced by arachidonic acid, indicating that marchantinquinone did not affect the activity of cyclooxygenase and thromboxane synthase. Marchantinquinone did inhibit the rising intracellular Ca2+ concentration stimulated by the five platelet-aggregation inducers. The formation of inositol monophosphate induced by thrombin was inhibited by marchantinquinone. Platelet cAMP and cGMP levels were unchanged by marchantinquinone. The results indicate that marchantinquinone exerts antiplatelet effects by inhibiting phosphoinositide turnover. [source] The effects of vasoactive agents, platelet agonists and anticoagulation on thrombelastographyACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2007J. Kawasaki Background:, Platelet activation is a critical step in primary hemostasis and clot formation. We tested a hypothesis that platelet stimulating effects of vasoactive agents or platelet agonists could be shown using thrombelastography (TEG®) as faster onset or increased clot strength. We further examined if TEG® could be modified to evaluate activated platelets as a reversal of anticoagulation in the presence of partial thrombin inhibition. Methods:, Blood samples were obtained from 126 non-cardiac surgical patients. Effects of vasoactive agents on TEG® and aggregometry were examined using epinephrine, norepinephrine, vasopressin, desmopressin acetate, milrinone and olprinone (Experiment I). Platelet agonists (epinephrine, ADP and collagen) were separately tested on TEG® (Experiment II). Effects of platelet agonists (ADP and collagen) on TEG® under anticoagulation in the absence or presence of abciximab were studied (Experiment III). We also tested antiplatelet effects of milrinone and olprinone in the presence of anticoagulants on TEG® (Experiment IV). Results:, Neither vasoactive agents nor platelet agonists affected TEG® or aggregometry results except for milrinone and olprinone on aggregometry (Experiment I, II). Platelet agonists facilitated clotting in the presence of anticoagulants (Experiment III). Abciximab-treated platelets still exhibited procoagulant effects in the presence of heparin, while not in the presence of argatroban (Experiment III). Platelet inhibition on the modified TEG® was more extensive with milrinone than olprinone, and it was dose dependent (Experiment IV). Conclusion:, Modified TEG® using heparin or argatroban might delineate the procoagulant effects of platelets by adding platelet specific agonist. [source] Aspirin, 110 years laterJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2009C. PATRONO Summary., Although conceived at the end of the 19th century as a synthetic analgesic agent with improved gastric tolerability vs. naturally occurring salicylates, acetylsalicylic acid (marketed as aspirin in 1899) turned out to be an ideal antiplatelet agent about 90 years later, following the understanding of its mechanism of action, the development of a mechanism-based biomarker for dose-finding studies, and the initiation of a series of appropriately sized, randomized clinical trials to test its efficacy and safety at low doses given once daily. At the turn of its 110th anniversary, aspirin continues to attract heated debates on a number of issues including (i) the optimal dose to maximize efficacy and minimize toxicity; (ii) the possibility that some patients may be ,resistant' to its antiplatelet effects; and (iii) the balance of benefits and risks in primary vs. secondary prevention. [source] Flavonoid inhibition of platelet procoagulant activity and phosphoinositide synthesisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2003R. Bucki Summary., Dietary flavonoids are known for their antiplatelet activity resulting in cardiovascular protection. Phosphatidylinositol 4,5-bisphosphate (PIP2) was previously reported to play a direct role in phosphatidylserine (PS) exposure, as a Ca2+ target. Thrombin formation and platelet procoagulant activity are dependent on PS exposure. As flavonoids can inhibit phosphoinositide (PPI) kinases, we examined whether changes in PPI metabolism in flavonoid-treated platelets could be involved in their antiplatelet effects. Treatment with the flavonoids quercetin or catechin reduced PS exposure, thrombin formation, PIP2 level and resynthesis after platelet activation with collagen, thrombin or calcium ionophore. Flavonoids also prevented [Ca2+]i increase induced by collagen, but not by the ionophore. The ability of flavonoids to decrease PS exposure induced by ionophore treatment could result from the diminution of PIP2 levels, whereas PS exposure induced by collagen could also be diminished by flavonoids' effects on calcium signaling dependent on PIP2 hydrolysis. These data favor a role for PIP2 in the antiplatelet effects of flavonoids. [source] Casual Chocolate Consumption and Inhibition of Platelet FunctionPREVENTIVE CARDIOLOGY, Issue 4 2007Bryan Bordeaux DO Observational studies have associated reduced cardiovascular mortality with chocolate consumption. Feeding studies of high-dose, flavanol-rich chocolate show antiplatelet effects, but the effect of casual chocolate consumption on platelet function is unknown. Healthy adults (N=1535) were proscribed from consuming foods affecting platelet function, including chocolate, for 48 hours and completed a 24-hour dietary recall before ex vivo platelet testing with the Platelet Function Analyzer (PFA)-100 (Dade Behring, Inc, Deerfield, IL) test and in vivo testing with urinary 11-dehydro thromboxane B2 (Tx-M) measurements. Some participants (n=141) reported ignoring the prohibition of consuming chocolate before platelet testing. Despite having similar baseline characteristics, chocolate consumers had longer PFA closure times (130 vs 123 seconds, P=.005) and decreased Tx-M levels (175 vs 290 ng/mol creatinine, P=.03). Chocolate remained a significant independent predictor of both ex vivo and in vivo platelet function testing after adjusting for confounders. The authors concluded that even consuming modest amounts of commercial chocolate has important antiplatelet effects. [source] Synthesis, Antiplatelet and Vasorelaxing Activities of Xanthone DerivativesARCHIV DER PHARMAZIE, Issue 1 2009Kai-Wei Lin Abstract A series of ,-aminoalkoxylxanthones was synthesized and tested in vitro for their ability to inhibit platelet aggregation and cause vasorelaxing action. Compounds 4, 5, 12, 17, and 18 showed significant antiplatelet effects on thrombin-, arachidonic acid (AA)-, collagen-, and platelet activating factor (PAF)-induced washed rabbit platelet aggregation and exhibited inhibition of primary and secondary aggregation induced by adenosine-5'-diphosphate (ADP) in human platelet-rich-plasma (PRP). Compounds 4, 17, and 18 revealed vasorelaxing activities in rat thoracic aorta. We concluded that these compounds may be developed as new antithrombotic agents. [source] | ||||||||||