Stability and sterility of a recombinant factor viii concentrate prepared for continuous infusion administration

Minipumps may facilitate cost‐effective and convenient continuous infusion (CI) therapy for severe hemophilia A. This study evaluated the in vitro sterility, ability to support bacterial growth, and specific activity stability of a recombinant factor VIII (FVIII; Bioclate™, Centeon) delivered by simulated CI at a variety of temperatures and after the addition of heparin or antibiotic. Closed system CIs of Bioclate™ (89.5 IU/ml) with and without heparin were sampled and cultured over a 6 day period. Bioclate™ (53.7 IU/ml) with and without heparin or vancomycin was inoculated with 102‐105 CFU/ml of S. aureus, S. epidermidis, Escherichia coli, E. cloacae, or Y. enterocolitica and assessed by quantitative culture after 1 and 3 days. The stability of Bioclate™ (50, 100, and 250 IU/ml) at three temperatures (21°C, 37°C, and 39°C) with and without heparin or vancomycin was tested over a period of 28 days. FVIII activity was measured in triplicate by a chromogenic assay (Coamatic® Factor VIII, Chromogenix) and purity evaluated by Western blot. No bacterial growth was detected during CI of FVIII for up to 6 days. Following bacterial inoculation, there was rapid growth (>3 log increase) of all tested bacterial species except S. aureus which only displayed a 1 log expansion at 3 days. The addition of heparin containing 9.45 μg/U benzyl alcohol had no effect on bacterial growth. The addition of vancomycin caused a modest suppression of S. aureus growth but not of E. coli. Diluent alone did not support bacterial growth. Neither concentration, increased temperature, nor the addition of heparin or vancomycin had a significant effect on FVIII activity stability. Samples retained >75% baseline activity for between 3 and 7 days, except the infusion of Bioclate™ 50 IU/ml plus heparin maintained at 21°C which remained stable for 28 days. Western blot analysis supported the activity assay findings. Standard and concentrated preparations of Bioclate™ are suitable for CI when delivered by the MiniMed® 404‐SP minipump. Because of the observed nutritive capability of this FVIII concentrate for sustaining bacterial growth, any contamination could result in systemic infection. Am. J. Hematol. 62:13–18, 1999. © 1999 Wiley‐Liss, Inc.