Factor VIII pharmacokinetics: intermittent infusion versus continuous infusion.

During the last few years, the purity of clotting factor concentrates has increased, especially with the advent of products derived from recombinant DNA technology. Clearly, a standard technique is needed when evaluating the in vivo behavior of these new products in hemophiliacs. The general principles of pharmacokinetics have been applied to the study of clotting factor concentrates, and the most useful kinetic parameters have been defined according to single- or repeated-dose studies. A comparison between different schedules of treatment by repeated bolus infusions has indicated that the dose reduction at steady state is inversely related to the time interval between administration. When factor concentrate is delivered by continuous infusion, the time interval is zero and the saving is maximum. The advantages of continuous infusion are particularly evident in hemophiliacs undergoing surgery.