The effects of recombinant hirudin on various platelet functions

The effect of two recombinant hirudins, HBW 023 (Hoechst AG, Frankfurt, FRG) and CGP 39393 [recy(tyr 63)] (Ciba Geigy, Basel, Switzerland) on various platelet functions has been investigated in blood samples of healthy volunteers anticoagulated with hirudin at concentrations of 10, 30, 50 micrograms/ml blood. Spontaneous aggregation was rarely observed in hirudinized platelet-rich plasma (PRP) compared to citrate-PRP. In comparison with citrate-PRP, both hirudins reduced the maximal response to epinephrine, but had no influence on the maximal response to ADP. Both hirudins reduced platelet adhesion to siliconized glass and inhibited platelet spreading compared to citrate-PRP. If hirudin was added to citrate-PRP, platelet count, epinephrine-induced aggregation, platelet spreading and adhesion remained unchanged while the maximal response to ADP increased. If citrate was added to hirudin-PRP, the maximal response to epinephrine as well as platelet spreading and adhesion increased to the extent observed in citrate-PRP. The effects of hirudin on platelet function are more pronounced than those of unfractionated heparin.