Evaluation of Recombinant Human Factor IX: Pharmacokinetic Studies in the Rat and the Dog

The pharmacokinetics of intravenously administered recombinant human factor IX (rhFIX) were studied in Sprague-Dawley rats and Beagle dogs. Rats received rhFIX (50 IU/kg once daily) for 28 days, and the plasma half-life was 5 h. Anti-Human Factor IX serum antibody levels were found in only 1 of 12 rats. The pharmacokinetic profiles of rhFIX or Mononine, a purified human plasma-derived factor IX, after single 100 IU/kg IV doses in dogs, were similar. Peak plasma concentrations of rhFIX and Mononine were 45 μg/ml. The mean plasma half-lives were 13.2±1.6 h for rhFIX and 13.2±1.6 h for Mono nine. Dogs also received rhFIX (40 IU/kkg IV, daily) for 28 days or Mononine (40 IU/kg IV daily) for 14 days