Expected FIX activity levels after rFIXFc or rFIX. Shown are expected FIX activity after doses (50 IU/kg body weight) of rFIXFc or rFIX administered intravenously at time 0 hours and followed for the specified intervals. The immediate postdose recovery giving a FIX activity level of 50% is as expected for both the short-acting rFIX and the extended t1/2 rFIXFc. The red line indicates the hours when the FIX activity level is <2% in this individual after taking the short-acting rFIX, and thus when he would be at risk of bleeding. Although the lines represent 1 individual's experience with the 2 different FIX preparations, the vertical lines represent the range of FIX activity levels for most persons with hemophilia. (Figure modified with permission from Powell et al.28 )
