A rationale for the therapeutic action of aprotinin.

Aprotinin, a protease inhibitor, has been used in a wide variety of pathophysiological states thought to be associated with an increase in protease activity. Opinion differ with respect to the success of the therapy. This paper proposes a rationale for the therapeutic action of aprotinin based on biochemical and physiological evidence. In the kallikrein-kinin system, in addition to kallikrein, other serine-esterases such as trypsin, plasmin, etc. can generate kinin production. In certain disease states such as pancreatitis there is not only an increase in serine-protease activity but frequently these enzymes reach parts of the organism where they are not found in health. Thus in such circumstances increased production of kinins can result. The consequences of increased kinin generation are discussed in light of work indicating their role in metabolic and circulatory homeostasis. Aprotinin is specifically a serine-esterase inhibitor. It is suggested that perhaps the most important action of this compound is as an inhibitor of the kallikrein-kinin system. On this basis a therapeutic regime in various disease states for the use of aprotinin, which allows for control of kinin generation, is suggested.