Efficacy of porcine factor VIII in the management of haemophiliacs with inhibitors.

We report our experience with polyelectrolyte-fractionated highly purified porcine factor VIII concentrate (Hyate:C). Porcine factor VIII concentrate was used to treat 14 haemorrhagic episodes including seven severe haemarthroses, three severe haematomata, two episodes of oral bleeding, one traumatic and the other after multiple dental extractions and two life-threatening intestinal haemorrhages. Altogether 60 infusions of Hyate:C were given to five haemophiliacs with inhibitors. At the time of the first infusion with porcine factor VIII the anti-human inhibitor level ranged from 60 to 2.5 modified Bethesda units/ml (MBU 4 h incubation). The porcine cross-reactivity of these inhibitors was 25.6% and 5.4% of the human inhibitor level in two patients and scarcely measurable in the other three patients. We injected an amount of porcine factor VIII concentrate corresponding to the calculated porcine neutralizing units plus the units required for haemostasis. The clinical efficacy was excellent and no adverse effects were encountered, apart from two episodes of mild pyrogenic reactions well controlled by hydrocortisone. The anamnestic antibody response against human factor VIII was of slight degree in all cases, while the porcine cross-reactivity showed no significant variation. Our results emphasize the role of porcine factor VIII in the treatment of haemophiliacs with inhibitors.