Aprotinin is a novel and potent small protein serine protease / bovine pancreatic trypsin inhibitor (BPTI) with antifibrinolytic activity. It inhibits trypsin and chymotrypsin with Kis of 0.06 pM and 9 nM, respectively. Aprotinin is used to reduce perioperative blood loss and transfusion. The use of aprotinin did not significantly increase the risk of renal failure or the need for postoperative renal replacement despite an increase in the proportion of patients who had a doubling of serum creatinine levels. The adjudication of death did not identify renal failure as contributing to or causing death associated with aprotinin use. A Meta analysis by Brown and colleagues showed a nonsignificant relative risk of renal failure with high-dose aprotinin.