Use of high dose factor VIIa in hemophilia patients

Management of haemophilic patients with inhibitors in major orthopaedic surgery by immunadsorption, substitution of factor VIII and recombinant factor VIIa (NovoSevenR): a single centre experience

Inhibitors of factor VIII or FIX in haemophilic patients are a common and serious complication associated with an increased risk of life-threatening bleeding during elective surgery. Substitution therapy fails to be effective, therefore an alternative treatment is needed. We have performed six major elective orthopaedic interventions in four patients with haemophilia A and inhibitors. A preoperative immunadsorbant therapy with Therasorb to eliminate inhibitors was successful in four cases, but during FVIII substitution inhibitors increased on day 4 to day 6 after surgery, leading to decreasing FVIII levels. Therefore, therapy was changed to recombinant FVIIa (rFVIIa; NovoSeven). Two interventions had to be covered with sole rFVIIa therapy as immunadsorbant therapy failed to be effective in one case and the need for acute intervention did not allow pretreatment in the other. We did not see increased bleeding during or after surgery when compared to our experience with non-inhibitor haemophilic patients. In conclusion, a preoperative decrease of inhibitors from immunadsorbant therapy, perioperative substitution of FVIII and changing treatment to rFVIIa when inhibitors are increased, is a safe and economic therapy for guaranteeing haemostasis in major elective orthopaedic surgery. On the contrary, sole therapy with rFVIIa allows immediate surgical intervention without a long hospital stay prior to surgery and a need for laboratory monitoring of inhibitor titres and FVIII levels. Our findings support data previously published.

Recombinant factor VIIa: review of efficacy, dosing regimens and safety in patients with congenital and acquired factor VIII or IX inhibitors

Recombinant factor (rF)VIIa has been available to clinicians since 1996 and has an excellent safety record after almost three-quarters of a million doses have been administered. This paper will review the current clinical experience with rFVIIa dosing in acquired and congenital hemophilia with inhibitors and chronicle all spontaneous and clinical trial reports of thrombotic adverse events as of April 2003. Standard dosing of rFVIIa (90 micro g kg(-1)) allows binding of FVIIa to the surface of an activated platelet and can directly activate factor X in the absence of tissue factor. Experience with bolus dosing suggests that higher dosing (>200 micro g kg(-1)) may be more efficacious in treating hemophilia patients. Clinical trials are ongoing to validate this observation. Continuous infusion dosing may be efficacious for major surgery but high infusion rates (50 micro g kg(-1) h(-1)) might be needed. The relationship between dose of rFVIIa, amount of thrombin generated and measurable FVIIa level is still not known and perhaps newer testing which measures thrombin generation might be more advantageous. Relatively few thrombotic events have been associated with rFVIIa. Known factors predisposing to thrombosis were present in 20 of the 25 (80%) hemophilia patients who were reported spontaneously or who developed a thrombosis during a clinical trial. Additionally, thrombotic events have not increased despite a growing experience with higher dosing of rFVIIa.