- To evaluate the changes in the levels of TXB2 and 12-HETE in serum at 12 and 24 hours after administration of aspirin and the changes in the levels of 11-dehydro TXB2 urinary 8-iso-PGF2 alpha urinary, 2-3 dinor-6-chetoPGF1 alpha, Verify-NOW Aspirin, platelets crosslinked at 12 and 24 hours after administration of aspirin