Rationale for the use of high dose rFVIIa in a high-titre inhibitor patient with haemophilia B during major orthopaedic procedures.

This is a case report of a child with severe hemophilia B and high titer factor IX inhibitor who was not achieving good hemostasis on conventional doses of rFVIIa. Pharmacokinetic studies showed that he required higher doses of rFVIIa (240-320 μg/L) to maintain adequate levels of rFVIIa and achieve satisfactory hemostasis, due to higher clearance rate in children.

The patient was able to receive weight-traction therapy to correct knee flexion deformity, as well as casting and wedging procedures and vigorous physiotherapy by giving rFVIIa 240 μg/kg every 6 hr initially, which was gradually reduced to once daily. This case report illustrates the requirement of dose flexibility and higher doses in children, and effectiveness of rFVIIa as prophylactic therapy in rehabilitation and orthopedic procedures.

– M. Aldouri.