PK/PD studies. (A) ALX-0081 plasma concentrations. (B) VWF-RiCof activity. (C) Ristocetin-induced vWF binding to platelets as assessed by flow cytometry. ALX-0081 doses: (●) 1.25 mg/kg; (□) 2.5 mg/kg; (shaded triangle) 5 mg/kg; (▪) vehicle. (D) Platelet adhesion on a collagen-coated surface under high shear stress (3000 sec⁻¹) expressed as percentage of the surface covered by platelets. *P < .05 vs vehicle and tirofiban; n = 5 per group.