Inhibitory effect of hirudin on thrombosis induced by prothrombin complex concentrates

The influence of hirudin on thrombus formation induced by prothrombin complex concentrate (PCC) was studied in two different test series in rats. Within the first test series hirudin was i.v. administered to the animals 10 min before they received PCC. Complete prevention of thrombus formation required a hirudin dose of 0.2 mg/kg. Within the second test series hirudin was added to the transfusion unit of PCC before application of PCC was started. In this case complete prevention of thrombus formation was yielded by addition of 140 micrograms hirudin to the PCC transfusion unit. In comparison with heparin and the synthetic thrombin inhibitor N alpha-(2-naphthylsulfonyl-glycyl)-4-amidinophenylalanine piperidide, hirudin was most potent.