 Tranexamic acid is administered intravenously to prevent bleeding associated with cardiac surgery and cardiopulmonary bypass. We have developed an assay for tranexamic acid. We have developed an alternative dosing schedule for tranexamic acid. The objective of this preliminary study is to determine if this new dosing schedule can achieve the desired plasma concentration of tranexamic acid and reduce intra and inter patient variability in tranexamic acid plasma concentrations relative to the current dosing schedule. 