AspirinAnti-Inflammatory Agents, Non-SteroidalSensitivity and SpecificityPlatelet Aggregation InhibitorsCyclooxygenase InhibitorsIbuprofenCyclooxygenase 2 InhibitorsThromboxane B2TiclopidineNaproxenDiclofenacSalicylatesPlatelet AggregationDrug Therapy, CombinationPlatelet Function TestsGastrointestinal HemorrhageGastrointestinal DiseasesStomach UlcerCyclooxygenase 1Prostaglandin-Endoperoxide SynthasesAcetaminophenDose-Response Relationship, Drug