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Pharmacokinetic studies were conducted in 20 patients with severe hemophilia A in North America. In this comparative pharmacokinetic study, Helixate FS (antihemophilic factor (recombinant)) was shown to be similar to its predecessor product HELIXATE. Mean FVIII recovery measured 10 minutes following infusion was 2.1 ± 0.3 %/IU/kg for Helixate FS (antihemophilic factor (recombinant)) and 2.4 ± 0.7 %/IU/kg for HELIXATE. The two recoveries were not statistically different (confidence interval 0.815–1.01). The mean biological half-life of recombinant FVIII formulated with sucrose (rFVIII-FS) is similar to HELIXATE with a mean of approximately 13 hours, which has previously been shown to be similar to plasma-derived Antihemophilic Factor (AHF). The activated partial thromboplastin time shortened appropriately with both rFVIII and rFVIII-FS. The recovery and half-life data for rFVIII-FS were unchanged after 24 weeks of exclusive treatment indicating continued efficacy and no evidence of FVIII inhibition. The mean FVIII recovery measured 10 minutes following a dose of rFVIII-FS in 37 patients (after 24 weeks of treatment with rFVIII-FS) was 2.1%/IU/kg, which was unchanged from FVIII recovery determined at baseline and at weeks 4 and 12.
Seventy-one patients with severe hemophilia A, ages 12–59, who had been previously treated with other recombinant and with plasma-derived AHF products, were enrolled in 6-month studies of home therapy with rFVIII-FS in Europe and North America. A total of 3995 infusions have been administered under this portion of the study, or 7.4 million units of rFVIII-FS. Treatment of 659 bleeding episodes during the study period required 951 infusions of rFVIII-FS. The majority of bleeding episodes (89.5%) were treated successfully with one or two infusions, using a mean dosage of approximately 28 IU/kg per treatment infusion. Regularly scheduled treatment accounted for 76% of infusions administered on study. Nine patients have received rFVIII-FS on 11 occasions for surgical procedures. The procedures included removal of a brain tumor, two total knee replacements, two joint synovectomies (one with Achilles tendon lengthening), two circumcisions, a hernia repair, and three teeth extractions. Hemostasis was satisfactory in all cases.
In clinical studies, Helixate FS (antihemophilic factor (recombinant)) has been used in the treatment of bleeding episodes in previously untreated patients (PUPs) and minimally treated (MTP) pediatric patients. In ongoing studies, 61 PUPs/MTPs have been treated with Helixate FS (antihemophilic factor (recombinant)) . Bleeding episodes were treated effectively with one or two infusions of rFVIII-FS. Ten patients have developed inhibitors. In these trials, approximately half of the patients have achieved 20 or more exposure days, and the incidence of inhibitor formation (15%) is consistent with that observed in other pediatric studies using plasma-derived and recombinant factor VIII products.2-5
2. Scharrer I, Bray GL, Neutzling O: Incidence of inhibitors in haemophilia A patients — a review of recent studies of recombinant and plasma-derived factor VIII concentrates. Haemophilia 5(3):145-154, 1999.
3. Lusher JM, Arkin S, Abildgaard CF, et al: Recombinant factor VIII for the treatment of previously untreated patients with hemophilia A: safety, efficacy, and development of inhibitors. N Engl J Med 328(7):453-459, 1993.
4. Schwarzinger I, Pabinger I, Korninger C, et al: Incidence of inhibitors in patients with severe and moderate hemophilia A treated with factor VIII concentrates. Am J Hematol 24(3):241–5, 1987.
5. Ehrenforth S, Kreuz W, Scharrer I, et al: Incidence of development of factor VIII and factor IX inhibitors in hemophiliacs. Lancet 339(8793):594–8, 1992.
Last reviewed on RxList: 1/30/2009
This monograph has been modified to include the generic and brand name in many instances.
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