Prohemostatic therapy: the rise and fall of aprotinin

Aprotinin has been used clinically to enhance hemostasis for decades and was approved in the United States by the Food and Drug Administration in 1993 to reduce the transfusion requirement during coronary artery bypass surgery. Marketing of aprotinin ceased recently when observational studies and a randomized clinical trial reported increased cardiovascular toxicity in patients receiving this drug. The importance of prohemostatic therapy is reviewed in light of new information on long-term deleterious effects of blood transfusion, including increased risk of cardiovascular disease, malignancy, and infection possibly attributable to delivery of a load of red cell-derived redox-active iron. Weaknesses in design of clinical trials that failed to control adequately for such alternative mechanisms of toxicity complicate interpretation of risks versus benefits in clinical trials of aprotinin given to reduce transfusion requirement in the acute surgical setting. Properties and applications of aprotinin that may not have received sufficient attention in the decision to remove this drug from the therapeutic armamentarium are reviewed. Potential application of prohemostatic drugs, including aprotinin to special populations at risk for operative blood loss requiring transfusion, is illustrated by the description of nine patients with coagulopathies whose operative bleeding was managed effectively with aprotinin. This drug may remain safe and effective in patients at risk of bleeding with surgery. Beneficial effects of aprotinin seemingly unrelated to its prohemostatic properties, especially its apparent striking antineoplastic effects, warrant further study.