Antihemophilic Factor [Factor VIII]
Indications
Treatment and prophylaxis of haemorrhagic episodes in patients with haemophilia A, Prophylaxis in severe haemophilia A
Pharmacology
Factor VIII is required for clot formation and maintenance of haemostasis. It activates factor X in conjunction with activated factor IX. Activated factor X then converts prothrombin to thrombin, which converts fibrinogen to fibrin, and forms a stable clot with factor XIII. Factor VIII is used for replacement therapy in patients with haemophilia A.
Dosage & Administration
Treatment and prophylaxis of haemorrhagic episodes in patients with haemophilia A: Dosage is individualised based on coagulation tests performed before treatment and at regular intervals during treatment. Generally, 1 IU/kg will increase circulating factor VIII levels by about 2 IU/dL. Recommended doses vary according to the preparation used
Suggested doses: Mild-moderate haemorrhage (increase to 20-30% of normal): Usually with a single dose of 10-15 IU/kg
More serious haemorrhage or minor surgery (increase to 30-50% of normal): Usual initial dose of 15-25 units/kg followed by 10-15 IU/kg every 8-12 hr if required
Severe haemorrhage or major surgery (increase to 80-100% of normal): Usual initial dose of 40-50 IU/kg followed by 20-25 IU/kg every 8-12 hr. Refer to individual product information for further dosing details
Prophylaxis in severe haemophilia A: 10-50 IU/kg every 2-3 days, as needed
Suggested doses: Mild-moderate haemorrhage (increase to 20-30% of normal): Usually with a single dose of 10-15 IU/kg
More serious haemorrhage or minor surgery (increase to 30-50% of normal): Usual initial dose of 15-25 units/kg followed by 10-15 IU/kg every 8-12 hr if required
Severe haemorrhage or major surgery (increase to 80-100% of normal): Usual initial dose of 40-50 IU/kg followed by 20-25 IU/kg every 8-12 hr. Refer to individual product information for further dosing details
Prophylaxis in severe haemophilia A: 10-50 IU/kg every 2-3 days, as needed
Interaction
Allergic reactions e.g. chills, chest tightness, fever, headache, hyperfibrinogenaemia, jittery feeling, lethargy, nausea, vomiting, somnolence, stinging at infusion site, stomach discomfort, tingling, urticaria, vasomotor reactions with rapid infusion.
Contraindications
In individuals who have had an anaphylactic or severe systemic reaction to antihemophilic factor or von Willebrand factor preparations.
Side Effects
Allergic reactions e.g. chills, chest tightness, fever, headache, hyperfibrinogenaemia, jittery feeling, lethargy, nausea, vomiting, somnolence, stinging at infusion site, stomach discomfort, tingling, urticaria, vasomotor reactions with rapid infusion.
Pregnancy & Lactation
Pregnancy Category C. Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
Precautions & Warnings
Risk of intravascular haemolysis in patients with blood groups A, B, or AB receiving high doses or repeated doses of factor VIII preparations. Risk of transmission of some viral infections especially hepatitis B and C. Dose requirement may vary in patients with factor VIII inhibitors; thus optimal treatment should be based on clinical response. Monitor platelet counts regularly during treatment.
Therapeutic Class
Antihaemophilic factor
Reconstitution
Intravenous: Treatment and prophylaxis of haemorrhagic episodes: If refrigerated, warm dried concentrate and diluent to room temperature before reconstitution.
Storage Conditions
Store between 2-8° C. Use within 3 hr of reconstitution; do not refrigerate after reconstitution due to risk of precipitation.
