Toxicological studies with recombinant hirudin.

After daily administration of 1 mg/kg over a period of 4 weeks, hirudin did not influence growth and general behaviour of the animals. There was no indication of treatment-related effects on the liver and the kidneys, on number and function of thrombocytes, on number and differentiation of white cells or on the erythrocytic system. Haemorrhagic complications did not occur. Formation of antibodies was not detectable. Histopathological changes due to application of r-hirudin were not found. LD50 is greater than 50 mg/kg body weight for intravenous application.