Coagulation Factor IXa, Factor XIa, Factor XIIa and plasma kallikrein

This target group represents the serine proteases of the contact activation and intrinsic pathways of the coagulation cascade, specifically Coagulation Factor IXa, Factor XIa, Factor XIIa, and Plasma Kallikrein. These enzymes function in a sequential proteolytic manner: Factor XIIa activates Factor XI, which then activates Factor IX, ultimately leading to the activation of Factor X and the generation of thrombin (StatPearls, 2023). Simultaneously, Factor XIIa and Plasma Kallikrein interact to drive the kinin-kallikrein system, resulting in the production of bradykinin, a key mediator of inflammation and vascular permeability (PubMed, PMC4941003). Historically, these factors were targeted collectively by broad-spectrum anticoagulants like heparin (via antithrombin) or protease inhibitors like aprotinin (DrugBank, DB00039). Modern therapeutic strategies often focus on individual components, such as Factor XIa or XIIa, to decouple antithrombotic efficacy from bleeding risk, as these factors are more critical for pathological thrombosis than for physiological hemostasis (PubMed, PMC4941003). Additionally, inhibitors of plasma kallikrein and Factor XIIa are vital in managing hereditary angioedema by preventing excessive bradykinin production (UniProt, P03952).

Other names

Contact activation pathway proteasesIntrinsic pathway factorsContact system factorsSerine proteases of the contact system

Inhibition of the proteolytic activity of serine proteases within the intrinsic coagulation cascade and the contact system to prevent thrombin generation and bradykinin release.