Von Willebrand factor (Specialist drug)

eMC §4.2 (Willfact 1000 IU powder and solvent for solution for injection). Treatment of von Willebrand disease should be supervised by a physician experienced in the treatment of haemostatic disorders. TARGETS: generally 1 IU/kg of von Willebrand factor raises the circulating VWF:RCo level by 0.02 IU/mL (2%); levels of VWF:RCo >0.6 IU/mL (60%) and FVIII:C >0.4 IU/mL (40%) should be achieved. Haemostasis cannot be ensured until FVIII:C reaches 0.4 IU/mL (40%). FACTOR VIII CO-ADMINISTRATION: a single injection of von Willebrand factor alone does not induce a maximum rise of FVIII:C for at least 6-12 hours, so where rapid correction of haemostasis is needed (haemorrhage, severe trauma, emergency surgery) and the baseline FVIII:C is below the critical level, a factor VIII product must be given with the first von Willebrand factor injection, at a dose calculated from the patient's baseline plasma FVIII:C. If an immediate rise in FVIII:C is not needed (e.g. planned surgery) or baseline FVIII:C is already sufficient, the physician may omit FVIII at the first injection. TIMING: give immediately before the intervention or as soon as possible after the onset of the bleed or severe trauma; in surgery give 1 hour before the procedure. ELECTIVE SURGERY: start Willfact 12-24 hours before surgery and repeat 1 hour before the procedure - co-administration of a factor VIII product is then not usually required because endogenous FVIII:C has usually reached 0.4 IU/mL (40%) before surgery, but confirm this in each patient. Dose and duration depend on clinical status, type and severity of bleeding, and both VWF:RCo and FVIII:C levels. OUTPATIENT/HOME TREATMENT may be initiated with the treating physician's approval, especially for minor to moderate bleeding or long-term prophylaxis, with appropriate training and review at predefined intervals. PAEDIATRIC (SPC text, expressed in IU/kg so not captured in the structured paediatric field): dosing is based on bodyweight for each indication, adjusted to clinical condition and VWF:RCo and FVIII:C plasma levels. For children below 6 years the initial dose may be guided by the patient's incremental recovery (IR) or, if IR data are not available, an initial dose between 60 and 100 IU/kg may be required, aiming to raise VWF:RCo to 100 IU/dL; for children above 6 years and adolescents the posology is the same as for adults. Subsequent doses in children and adolescents should be individualised to clinical condition and VWF:RCo levels. For elective surgery in children below 6 years, after a first dose given 12 to 24 hours before the procedure, the repeated dose may be given 30 minutes before the procedure; above 6 years the adult posology applies. For prophylaxis in children and adolescents, dose and re-administration frequency should be individualised to incremental recovery and VWF:RCo levels. Verify paediatric use against a children's formulary. NOTE: this product is a von Willebrand factor product with a LOW FVIII content - different VWF/FVIII products are not interchangeable; verify the specific brand before administration.