Humate-P Potency Units: Getting the Numbers Right in Clinical Practice

Humate-P’s labeling includes two potency values—one for VWF:RCo and one for Factor VIII (FVIII:C)—because it is a plasma-derived concentrate that contains both von Willebrand factor (VWF) and factor VIII.

Humate-P is a plasma-derived concentrate containing both von Willebrand factor (VWF) and factor VIII (FVIII), approved for use in von Willebrand disease (VWD) and hemophilia A.

Its labeling includes two potency values—VWF:RCo and FVIII:C—and knowing which number to use is essential to accurate dosing.

Why Two Potency Numbers Exist

VWF:RCo (ristocetin cofactor activity)
- Measures the functional activity of VWF in promoting platelet adhesion.
- Clinically relevant for VWD, where the defect lies in VWF quantity or function.
FVIII:C (factor VIII coagulant activity)
- Measures FVIII clotting activity.
- Relevant for hemophilia A, where FVIII is deficient or absent.

Since Humate-P contains both clotting proteins, it can be dosed for either condition—but the unit basis differs depending on the indication.

Dosing Decision: Which Number to Use

Quick rule:

VWD? → Use VWF:RCo IU
Hemophilia A? → Use FVIII:C IU

For mixed VWD + low FVIII, dose primarily based on VWF:RCo but monitor FVIII levels to ensure targets are met and avoid FVIII excess.

Clinical Application

Indication	Potency Value for Dose Calculation	Why It Matters
VWD (all types)	VWF:RCo IU	Directly corrects the VWF defect
Surgical prophylaxis in VWD	VWF:RCo IU	Maintains VWF for platelet adhesion during high-risk bleeding events
Hemophilia A	FVIII:C IU	Direct replacement of missing FVIII
Mixed VWD + low FVIII	VWF:RCo IU + monitor FVIII	VWF infusion stabilizes endogenous FVIII

Practical Pearls

VWF infusion naturally raises FVIII levels because VWF prolongs FVIII half-life.
FVIII:C values on the vial are typically lower than VWF:RCo values—don’t accidentally swap them.
Over-replacement of FVIII is a risk in prolonged therapy for VWD, especially perioperatively—monitor FVIII levels during repeated dosing.

Bottom line

Humate-P’s dual potency labeling is not a redundancy—it’s a dosing roadmap. Matching the potency value to the patient’s diagnosis ensures optimal clotting factor correction and minimizes risk.

https://labeling.cslbehring.com/PI/US/Humate-P/EN/Humate-P-Prescribing-Information.pdf

Dosing | HUMATE-P

Read about Humate-P Dosing.