Pharmacokinetic Studies of Factor Ⅷ in Chinese Boys with Severe Hemophilia A: A Single-Center Study

摘要

Background:Although much attention has been paid to the pharmacokinetics (PKs) of different factor Ⅷ (FⅧ) concentrates in persons with hemophilia A (HA),limited information is available in young boys with severe HA.In this study,we aimed to assess the PK parameters of FⅧ products in boys with severe HA in China.Methods:A total of 36 boys (plasma-derived [pd]-FⅧ,n =15;recombinant [r] FⅧ,n =21) were enrolled between January 2015 and May 2016 in Beijing Children's Hospital.PK characteristics of FⅧ products were studied according to a reduced 4-sampling time point design (1 h,9 h,24 h,and 48 h postinfusion).Results:The mean FⅧ half-life (t1/2) was 10.99 ± 3.45 h (range 5.52-20.02 h),the mean in vivo recovery (IVR) was 2.01 ± 0.42 IU/dl per IU/kg (range 1.24-3.02 IU/dl per IU/kg) and mean clearance (CL) of FⅧ is 4.34 ± 1.58 ml·kg-1·h-1 (range 2.29-7.90 ml·kg-1·h-1).We also analyzed the influence of several parameters that potentially modulate FⅧ PK.The age was closely associated with FⅧ half-life (R2 =0.32,P ＜ 0.01).The t1/2 of FⅧ increased by 0.59 h per year.Besides age,von Willebrand factor antigen (VWF∶Ag) also was associated with FⅧ half-life (R2 =0.52,P ＜ 0.01).Patients with blood Group O had a shorter FⅧ half-life than patients with non-O blood group (9.40 ± 0.68 h vs.12.3 ± 0.79 h,t =2.70,P =0.01).The FⅧ IVR correlated with age (R2 =0.21,P ＜ 0.01) and VWF:Ag level (R2 =0.28,P ＜ 0.01).CL rates were faster in young patients and in those with low-VWF:Ag levels.CL rates of FⅧ are higher in blood Group O versus non-blood Group O persons (5.02 ± 0.38 vs.4.00 ± 0.32 ml·kg-1 ·h-1,t =2.53,P =0.02).Conclusions:Chinese boys with severe HA have similar PK values to other ethnic groups and large differences in FⅧ PK between individual patients.Age,blood group,and VWF:Ag levels are important determining factors for FⅧ CL.