Intrinsic coagulation pathway

The **intrinsic coagulation pathway** (also called the **contact activation pathway** or **intrinsic pathway of blood coagulation**) is not a single molecular target but a biochemical cascade consisting of multiple plasma proteins (clotting factors), enzymes, and cofactors that work together to achieve **hemostasis** through blood clotting. It is triggered by internal vascular endothelial damage, which exposes negatively charged surfaces (such as collagen), leading to sequential activation of clotting factors XII, XI, IX, and VIII. This cascade ultimately activates factor X, which, together with factor V, forms the prothrombinase complex, leading into the common pathway of coagulation and resulting in the formation of insoluble fibrin strands to stabilize the platelet plug and arrest bleeding[1][3][4]. The intrinsic pathway is clinically assessed using the **partial thromboplastin time (PTT)** test and is implicated in disorders like hemophilia (due to factor VIII or IX deficiency) and thrombotic events. Critically, the "intrinsic coagulation pathway" should not be described as a direct therapeutic target, as it represents a multicomponent process, not an individual molecule, enzyme, or receptor that drugs bind to or modulate directly[1][5][4]. Important points regarding this entry: - This is not a single gene, protein, or druggable entity but a physiological pathway made up of several molecular targets. - Drugs acting on this pathway, such as anticoagulants, target individual factors (e.g., factor Xa inhibitors) rather than the entire pathway. - Its mention as a "target" is incorrect in strict pharmacological or molecular terms, so **is_incorrect: true**. For structured drug or biomarker information, specify individual clotting factors (XII, XI, IX, VIII) rather than the pathway as a whole[1][4][5].

Other names

intrinsic pathwaycontact activation pathwayintrinsic pathway of blood coagulation