Epsilon-aminocaproic acid inhibits the activity of factor VIII inhibitors in patients with severe haemophilia A in vivo and in vitro

Haemophilia patients with inhibitors pose a formidable challenge for patien t management. This is particularly problematic in developing countries, whe re porcine factor VIII, FEIBA, factor VIIa or immunoadsorption column are:g enerally unavailable or unaffordable. Under these circumstances, any effect ive modality of affordable treatment is welcome. We investigated, both in v ivo and in vitro, the effect of E-aminocaproic acid (EACA) on the inhibitor y activity of factor VI II inhibitor. It was found that in vitro EACA (fina l concentration 1.25-5 mg/ml) substantially inhibited the activity of the i nhibitors, while the same concentration of EACA had no effect on other immu nological reactions like red cell agglutination and immunofluorescence, The inhibitory action of EACA on factor VIII inhibitor was also confirmed in a n improvised antigen-binding ELISA system. Further, the inhibitory activity of EACA was confirmed in 2 patients, in whom the inhibitory activity persi sted for 15 min following infusion of EACA (100 mg/kg over 10 min). EACA wa s found to be even more effective in local wound application in patients of haemophilia A with inhibitors. EACA at the concentration cited did not act as an inhibitor of factor VIII inhibitor through occupancy of lysine bindi ng sites. The inhibitory activity of EACA on factor VIII inhibitor was equa lly seen with recombinant factor VIII also; hence this action cannot be exp lained by its antifibrinolytic activity. Copyright (C) 2000 S. Karger AG, B asel.