[Pharmacokinetic Study of Coagulation Factor Ⅷ in Adults with Severe Hemophilia A]

Objective: To detect the pharmacokinetic (PK) parameters of coagulation factor Ⅷ (FⅧ) in adult patients with severe hemophilia A, identify the potential factors influencing FⅧ PK, and optimize the use of FⅧ in individual prophylaxis regimens.

Methods: PK characteristics of FⅧ were studied in a total of 23 severe hemophilia A adults. The correlation of patients' characteristics including age, von Willebrand factor antigen (vWF:Ag), blood group, weight, body mass index (BMI) and FⅧ genotype, with FⅧ PK were evaluated. Individual prophylaxis regimens were given based on FⅧ PK parameters.

Results: The mean terminal half‑life (t_1/2) of FⅧ was 20.6±9.3 h, ranged from 11.47 h to 30.12 h. The age (r =0.580) and vWF:Ag (r =0.814) were significantly positively correlated with t_1/2 of FⅧ. The mean area under the plasma concentration curve (AUC) of FⅧ was 913±399 (328-1 878) IU·h/dl, and the AUC of FⅧ was positively correlated with age (r =0.557) and vWF:Ag (r =0.784). The mean residence time (MRT) of FⅧ was 24.7±12.4 (13.2-62.2) h, and the MRT of FⅧ was positively correlated with age (r =0.664) and vWF:Ag (r =0.868). The mean in vivo recovery (IVR) of FⅧ was 2.59±0.888 (1.5-4.29) IU/dl per IU/kg, the mean clearance (CL) of FⅧ was 3±1.58（0.97-7.18）ml/(kg·h)，and there was no significant correlation of IVR and CL with age and vWF:Ag. According to the individual PK parameters, ultra low-dose, low-dose and moderate-dose FⅧ were applied to 15, 6, 2 adults patients with severe hemophilia A for prophylaxis, respectively.

Conclusion: There are significant individual differences in the FⅧ half-life of adult patients with severe hemophilia A. The older the patient, the higher the vWF:Ag level, and the longer the FⅧ half-life. Individual administration is required based on the FⅧ PK parameters to optimize prophylaxis treatment.