Antihemophilic factor/von Willebrand factor complex (human)

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Antihemophilic factor/von Willebrand factor complex (human)

GRIFOLSSterile, lyophilized powder concentrate of antihemophilic factor and von Willebrand factor complex for surgical and/or invasive procedures in patients with von Willebrand disease

This agent is prepared from constituents of normal human plasma (antihemophilic factor/von Willebrand factor complex) that are required for clotting. The administration of this agent temporarily increases the plasma level of factor VIII, which decreases the hazard of hemorrhage. Factor VIII serves as an essential cofactor in the activation of factor X, leading to the formation of thrombin and fibrin. Von Willebrand factor promotes platelet aggregation and adhesion on damaged vascular endothelium and serves as a stabilizing carrier protein for factor VIII. This treatment was approved on January 31, 2007, for surgical and/or invasive procedures in patients with von Willebrand disease in whom desmopressin is either ineffective or contraindicated. The agent is not indicated for patients with severe von Willebrand disease who are undergoing major surgery. This replacement therapy was previously approved for the prevention and control of bleeding in patients with factor VIII deficiency due to hemophilia A or acquired factor VIII deficiency.

Safety. Thromboembolic events have been reported in patients with von Willebrand disease who were receiving this replacement therapy. Caution should be exercised and antithrombotic measures should be considered in patients at high risk for thromboembolic events. Because this agent is made from human plasma, it carries a risk of transmitting infectious agents. Patients receiving this treatment may develop signs and/or symptoms of viral infections, particularly hepatitis C. Rapid administration of this agent may result in vasomotor reactions. The agent should not be administered at a rate >10 mL/min. Patients may develop inhibitors (ie, antibodies) to this treatment; these inhibitors may decrease response to treatment, and larger doses of the agent may therefore be required. Patients experiencing early symptoms and signs of a hypersensitivity reaction should immediately discontinue treatment. The most common adverse events reported in association with this treatment include urticaria, fever, chills, nausea, vomiting, headache, somnolence, lethargy, pruritus, pharyngitis, paresthesia, rash, and hemorrhage.

Dosing. This lyophilized powder is available in potencies of 250 IU/5 mL, 500 IU/5 mL, 1,000 IU/10 mL, and 1,500 IU/10 mL single-dose vials. The concentrate must be reconstituted with sterile water for injection, and the resulting solution (warmed to room temperature) should be administered within 3 hours after reconstitution to avoid the potential effects of any inadvertent bacterial contamination that may have occurred during reconstitution. Dosing guidelines for adult and pediatric patients are based on body weight. Adult patients should receive a preoperative dose of 60 VWF:RCof IU/kg body weight, with subsequent infusions of 40 to 60 VWF:RCof IU/kg body weight at 8- to 12-hour intervals as needed. Dosing may be reduced after the third postoperative day. Treatment should continue until healing is complete. Adult patients undergoing minor or major procedures should be treated with VWF activity of 40% to 50% on postoperative days 1 to 3 (minor procedures) or on postoperative days 3 to ≥7 (major procedures). Pediatric patients should receive a preoperative dose of 75 VWF:RCof IU/kg body weight, with subsequent infusions of 50 to 75 VWF:RCof IU/kg body weight at 8- to 12-hour intervals as needed. Dosing may be reduced after the third postoperative day. Treatment should continue until healing is complete.