Factor Ix

What it is and how it works

Factor IX is a vitamin K-dependent serine protease precursor that, once activated, forms the intrinsic tenase complex with factor VIIIa and activates factor X, leading to thrombin generation and fibrin clot formation. Replacement temporarily corrects the factor IX deficiency in haemophilia B.

Indications

Treatment and prophylaxis of bleeding in patients with haemophilia B (congenital factor IX deficiency), including perioperative management.

Dosage and administration (summary)

Dosing is individualised by the haemophilia specialist according to body weight, severity of deficiency, site and extent of bleeding and target factor IX level, guided by clinical response and factor IX activity monitoring; it is given by slow intravenous injection.

Contraindications

Known hypersensitivity to the product or its excipients (including, for some products, mouse or hamster proteins).

Warnings and precautions

Patients should be monitored for development of factor IX inhibitors, which may be associated with anaphylaxis and nephrotic syndrome; hypersensitivity reactions require immediate discontinuation. Thromboembolic complications, including DIC, may occur, particularly with plasma-derived products in patients with liver disease, after surgery or in neonates; plasma-derived products carry a theoretical risk of transmitting infectious agents.

Pregnancy

Experience is limited because haemophilia B is rare in women; use only if clearly indicated.

Storage and supply

Store refrigerated at 2–8 °C (some products permit storage below 25 °C for a limited period); 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.