What is factor VIII

Factor VIII

Synonyms: antihemophilic globulin A, factor 8
English: factor VIII, anti-hemophilic factor

1 definition

The Factor VIII, also antihemophilic globulin A. called, is an important part of blood clotting. It is part of the endogenous coagulation system (intrinsic system). A deficiency leads to haemophilia A, an excess leads to thrombus formation with an increased risk of venous thrombosis and pulmonary embolism.

2 biosynthesis

The biosynthesis of factor VIII is not fully understood. Among other things, the protein is formed in the vascular endothelium and in the liver sinusoids and broken down in the liver and kidneys. The molecule consists of a heavy and a light chain and is encoded by the F8 gene. In the bloodstream it is mostly bound to the von Willebrand factor, with which it forms a complex.

3 coagulation cascade

After factor XII comes into contact with a negatively charged surface, factors XI and IX are activated. Factor IX forms an enzyme complex with phospholipids and calcium complexes, which activates factor X. This reaction is accelerated by factor VIII, which is additionally activated by thrombin that has already been formed. (See: blood clotting)

4 pharmacology

Antihemophilic Globulin A is used to treat hemophilia A. It can be obtained from human donor plasma as well as genetically engineered. The application is intravenous. A particular problem is the formation of antibodies (inhibitor formation) against factor VIII, which can occur in patients with haemophilia A. Inactivation of the factor continues to lead to bleeding (inhibitor hemophilia). Depending on the number of inhibitors in the blood of haemophilia patients, a distinction is made between low responders and high responders.

Recombinant factor VIII drugs include: