AspirinPlatelet Aggregation InhibitorsAnti-Inflammatory Agents, Non-SteroidalTiclopidineDrug Administration ScheduleDouble-Blind MethodThromboxane B2Drug Therapy, CombinationCyclooxygenase InhibitorsDose-Response Relationship, DrugPlatelet AggregationAdministration, OralSalicylatesTreatment OutcomeTime FactorsPlatelet Function TestsBlood PlateletsProspective StudiesSodium SalicylateWarfarinAnticoagulantsInfant, NewbornTablets, Enteric-CoatedFibrinolytic AgentsHemorrhage