Low recovery in vivo of highly purified factor VIII in patients with hemophilia.

To assess whether the response and recovery of highly purified factor VIII products approach the levels predicted by use of manufacturers' suggestions, we studied response in vivo and percentage of recovery in boys and men with hemophilia after infusion of 50 IU of an immunoaffinity-purified factor VIII preparation (Hemofil M) per kilogram of body weight. We also studied dose response and percentage of recovery in the same boys after infusion of a factor VII concentrate prepared by solvent detergent treatment and gel filtration (Koate-HP). For boys the difference between mean peak factor VIII response with Hemofil M (1.02% +/- 0.07%) and the response with Koate-HP (1.21% +/- 0.10%) was not significant (p = 0.10), but the response of both products was considerably less than the predicted response of 2.0%. The response to Hemofil M in men (1.38% +/- 0.12%) was significantly better than the response in boys (p = 0.004) but, again, fell short of the anticipated response of 2.0%. In boys the percentage of recovery of Hemofil M was 38.4% +/- 2.1%, compared with Koate-HP recovery, which was 47.0% +/- 3.6% (p = 0.034). The percentage of recovery in men was 47.5% +/- 2.8%. The better response observed in men appears to be, in part, a function of larger body size. We conclude that peak factor VIII response and recovery in boys and men who receive highly purified factor VIII concentrates are lower than those predicted by use of current prescribing recommendations.