Von Willebrand factor/factor VIII concentrate (Haemate(R) P) dosing based on pharmacokinetics: a prospective multicenter trial in elective surgery.

Background: While plasma-derived concentrates containing large amounts of von Willebrand factor (VWF) are effective in treating von Willebrand disease (VWD), optimal dosing remains to be fully characterized. Objectives: To determine the feasibility of dosing Haemate P-(R) VWF/factor VIII (FVIII) concentrate based on pharmacokinetics (PK) in the management of surgical subjects with VWD. Methods: VWD subjects scheduled for elective surgery were enrolled in a prospective multicenter open-label cohort study. A pre-operative loading dose of VWF/FVIII concentrate based upon prior individual subject PK analysis was administered followed by postoperative therapeutic/maintenance infusions. Results: Twenty-eight subjects with types 1, 2A or 3 VWD and one with type 2 M were enrolled. Median in vivo recovery of VWF ristocetin cofactor (VWF:RCo) was 1.9 IU dL(-1) (IU kg(-1))(-1) with an interquartile range (IQR) of 1.6-2.5 IU dL(-1) (IU kg(-1))(-1). Median response, half-life and clearance were 74.0% (IQR, 55.5-100%), 15.6 h (IQR, 9.0-28.4 h) and 3.26 mL kg(-1) h(-1) (IQR, 2.29-5.21 mL kg(-1) h(-1)), respectively. A PK-guided median VWF:RCo loading dose of 62.4 IU kg(-1) (IQR, 50.1-87.0 IU kg(-1)) was administered. Postoperative mean trough VWF:RCo levels of 62-73 IU dL(-1) were sufficient to prevent bleeding. Investigators rated hemostasis excellent or good in 96.3% of subjects on the day of surgery and 100% on the next day and on day 14. A subject with multiple risk factors developed pulmonary embolism, which resolved without sequelae. Conclusions: Haemate P-(R) provided effective and safe hemostasis in VWD subjects undergoing elective surgery. Selection of Haemate((R)) P loading dose on the basis of VWF PK proved feasible.