Evaluation of recombinant factor VIII (Kogenate) stability for continuous infusion using a minipump infusion device

Continuous infusion of recombinant factor VIII (rFVIII) is desirable in clinical settings in order to maintain haemostatic levels in a cost-effective manner. This study was designed to determine rFVIII stability over time using a minipump set-up, which has been employed by clinicians for continuous infusion of rFVIII. Vials from three lots of Kogenate (Bayer Corporation) were reconstituted in sterile water for injection, pooled and transferred to minipump infusion sets composed of either polyvinylchloride (Medex # IPR86/tube volume 0.5 mL) or polyethylene (McGraw S5904-52, tube and adapter volume 2.1 mL), and held in temperature-controlled rooms at 5 degrees C, 25 degrees C and 30 degrees C. Additional bags of rFVII were prepared with heparin (4 U mL-1), and maintained at 30 degrees C. rFVIII was infused at a rate of 1.0 mL h-1. Samples were analysed for rFVIII activity over a 7-day period at 0, 1, 15, 24, 78 and 168 h. Prior to the start of the timed study, rFVIII activity was measured in the lot pools and in the polyvinylchloride or polyethylene bags, and in the first flush volumes through the tubing. There was no difference in rFVIII activity measured in the pools compared to the bags. rFVIII levels in the initial 3-mL infusion through the tubing showed a slight decrease in activity compared to the initial level which amounted to an insignificant loss of activity for the polyvinylchloride tubing but a significant loss in the polyethylene tubing (approximately 10 IU absolute loss in polyvinylchloride vs. 100 IU loss in polyethylene). After an initial flush of 1.0 mL for polyvinylchloride and 5.0 mL for polyethylene, activity returned to baseline and subsequently remained stable for all time points and temperatures from 5-30 degrees C over the 7-day period. We conclude that the standard polyvinylchloride in polyethylene minipump bags and tubing provide excellent delivery and stability of rFVIII for continuous infusion with or without heparin, and can be used in hospital and ambulatory settings.