Factor Viii / Von Willebrand Factor

What it is and how it works

Von Willebrand factor mediates platelet adhesion to damaged subendothelium and platelet aggregation, and acts as a carrier that protects factor VIII from premature degradation. Factor VIII is the cofactor of factor IXa in activating factor X. Replacement of both corrects the haemostatic defect in von Willebrand disease and, through factor VIII, in haemophilia A.

Indications

Prevention and treatment of bleeding, including surgical bleeding, in von Willebrand disease when desmopressin is ineffective or contraindicated; treatment and prophylaxis of bleeding in haemophilia A (congenital factor VIII deficiency).

Dosage and administration (summary)

Dosing is individualised by the haemophilia specialist according to the type and severity of deficiency, body weight, bleeding site or surgery, and monitoring of factor VIII and VWF:RCo (ristocetin cofactor) activity; it is given by slow intravenous injection.

Contraindications

Known hypersensitivity to the active substances or excipients.

Warnings and precautions

Hypersensitivity reactions and development of neutralising antibodies (inhibitors) to factor VIII or VWF may occur, and patients should be monitored for inadequate response. Sustained excessive factor VIII levels increase the risk of thrombosis, particularly in patients with known risk factors; plasma-derived products carry a theoretical risk of transmitting infectious agents.

Pregnancy

Use only if clearly indicated; it may be needed to manage von Willebrand disease around delivery.

Storage and supply

Store at 2–8 °C or below 25 °C according to the product information; do not freeze; protect from light.

Source: reference summary prepared from the EU SmPC/EPAR, BNF and WHO Model Formulary. The approved product information in Iran governs.