SUPERIOR IN-VIVO RESPONSE OF RECOMBINANT FACTOR-VIII CONCENTRATE IN CHILDREN WITH HEMOPHILIA-A

Objective: Our previous experience with highly purified plasma-derived factor VI II (pdFVIII) concentrates showed that adult dosage recommen dations were not applicable to children. In this study, we compared th e in vivo response and recovery of recombinant factor VIII (rFVIII) wi th those of highly purified pdFVIII concentrate in children with hemop hilia A. Study design: Ten boys with severe factor VIII deficiency and no concurrent bleeding episodes participated in a masked, prospective ,:crossover study comparing factor VIII coagulant activity after infus ion of 50 units of pdFVIII and rFVIII products per kilogram of body we ight. Results: Mean peak factor VIII response with rFVIII was 1.91% +/ - 0.14%, significantly better than the response observed with highly p urified pdFVIII of 1.5% +/- 0.15% (p = 0.007). Mean peak factor VIII r ecovery was 100.5% with rFVIII versus 78.7% with pdFVIII (p = 0.007). Positive correlations between response to rFVIII and body surface area (r = 0.734, p = 0.015), body weight (r = 0.762, p = 0.01), and plasma volume (r = 0.659, p = 0.03) were observed. Conclusions: Infusion of rFVIII produced a significantly better response and recovery in vivo t han infusion of highly purified pdFVIII in children. The response in c hildren after infusion of rFVIII was similar to the response previousl y observed in adults.