What are the half-life and recovery of BeneFIX after infusion into patients with hemophilia B?
After single intravenous (IV) doses of 50 IU/kg of BeneFIX in 36 patients, each given as a 10-minute infusion, the mean increase in circulating factor IX activity was 0.8 0.2 IU/dL per IU/kg infused (ranged from 0.4 to 1.4 IU/dL per IU/kg), and the mean biological half-life was 18.8 5.4 hours (ranged from 11 to 36 hours).1 In an 11-patient crossover study comparing the pharmacokinetics of BeneFIX to a high-purity plasma-derived product, the in vivo recovery with BeneFIX was 28% lower than the recovery with a highly purified plasma-derived factor IX product. There was no significant difference in biological half-life. In subsequent evaluations at 6 and 12 months, the pharmacokinetic parameter estimates did not change.
