title: Platelet response to increased aspirin dose in patients with persistent platelet aggregation while treated with aspirin 81 mg.
abstract: This study demonstrates that patients who are taking 81 mg of aspirin and are nonresponsive benefit from a dose of 162 mg or greater vs a different antiplatelet therapy. We identified 100 patients who were nonresponsive to aspirin 81 mg via whole blood aggregometry and observed how many patients became responsive at a dose of 162 mg or greater. Platelet nonresponsiveness was defined as >10 Ω of resistance to collagen 1 µg/mL and/or an ohms ratio of collagen 1 µg/mL to collagen 5 µg/mL >0.5 and/or >6 Ω to arachidonate. Borderline response was defined as an improvement in 1 but not both of the above criteria. Of the initial 100 patients who were nonresponsive to an aspirin dose of 81 mg, 79% became responsive at a dose of 162 mg or >162 mg. Only 6% did not respond to any increase in dose. We believe that patients treated with low-dose aspirin who have significant risk for secondary vascular events should be individually assessed to determine their antiplatelet response. Those found to have persistent platelet aggregation despite treatment with 81 mg of aspirin have a higher likelihood of obtaining an adequate antiplatelet response at a higher aspirin dose.
authors.affiliation: Dent Neurologic Institute, Buffalo, NY, USA.|State University at Buffalo School of Pharmacy and Pharmaceutical Sciences, Buffalo, NY, USA.
authors.forename: Fran
authors.initials: F
authors.lastname: Gengo
authors.affiliation: Dent Neurologic Institute, Buffalo, NY, USA.
authors.forename: Erica S
authors.initials: ES
authors.lastname: Westphal
authors.affiliation: Dent Neurologic Institute, Buffalo, NY, USA.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Rainka
authors.affiliation: State University at Buffalo School of Pharmacy and Pharmaceutical Sciences, Buffalo, NY, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Janda
authors.affiliation: Dent Neurologic Institute, Buffalo, NY, USA.|Vanderbilt University School of Medicine, Department of Pharmacology, Nashville, TN, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Robson
authors.affiliation: Dent Neurologic Institute, Buffalo, NY, USA.
authors.forename: J Maurice
authors.initials: JM
authors.lastname: Hourihane
authors.affiliation: Dent Neurologic Institute, Buffalo, NY, USA.
authors.forename: Vernice
authors.initials: V
authors.lastname: Bates
mesh_terms: D001241:Aspirin / Q000008:administration & dosage*; D001780:Blood Coagulation Tests / Q000379:methods; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D010979:Platelet Function Tests / Q000379:methods
chemical_list: D010975:Platelet Aggregation Inhibitors; D003094:Collagen; D001241:Aspirin
keywords: TIA; aspirin; cardiology; platelet aggregation; platelet response; stroke