Activated Protein C (APC)

Activated protein C (with protein S as a cofactor) degrades Factor Va and Factor VIIIa. Activated protein C resistance is the inability of protein C to cleave Factor Va and/or Factor VIIIa, which allows for longer duration of thrombin generation and may lead to a hypercoagulable state. This may be hereditary or acquired. The best known and most common hereditary form is Factor V Leiden. Acquired forms occur in the presence of elevated Factor VIII concentrations.

Human activated protein C is a serine protease which is derived from the two chain vitamin K dependent zymogen.It is used to inhibit blood coagulation through the selective inactivation of the cofactors Va and VLLA.It is indicated for use in the treatment and reduction of mortality in cases of severe sepsis, though the mechanism by which it achieves this reduction is not clearly defined or understood.