Extended half-life clotting factor concentrates: results from published clinical trials.

Extended half-life clotting factor concentrates have been recently introduced into the armamentarium of treatments for patients with haemophilia A and B. In general, the data from published studies have demonstrated these products to be safe with no inhibitors reported in previously treated patients and efficacious with the advantage of a longer half-life allowing for less frequent intravenous infusions of factor. This enhanced convenience has led to some patients not previously on prophylaxis to begin prophylaxis while for others, especially children, has led to the ability to provide prophylaxis with reduced use of central venous catheters. The extended half-life factor IX products are now allowing patients to dose every 1-2 weeks while maintaining higher trough levels while the extended half-life factor VIII products have reduced the frequency of administration for patients on prophylaxis to as infrequent as once per week for some patients and to twice per week for all patients including younger children. It is important to note that data from previously untreated patients have not been published yet and the incidence for inhibitors in this patient population is as of yet unknown. The era of extended half-life clotting factor products has begun and the challenge for the haemophilia community will be how to best integrate these products into haemophilia clinical practice.