ABSTRACT
Hirudin is a specific, potent inhibitor of thrombin that may be a valuable antithrombotic agent. The aim of this study was to investigate the hypothesis that the haemostatic effects of DDAVP counteract the coagulation defect induced by hirudin. The effect of DDAVP was studied in vivo on the anticoagulant action of recombinant hirudin (CGP39393) in vitro. Blood samples were taken at intervals from 10 normal volunteers infused with DDAVP. Factor VIII:C rose from (mean) 0.68 IU/ml before DDAVP to 2.19 and 2.16 IU/ml after 30 and 60 min infusion, respectively. Samples taken during DDAVP infusion showed a dose related decrease in the hirudin (0.5 and 1.0 microM) induced prolongation of the APTT, that occurred at FVIII:C concentrations of up to twice normal. At higher concentrations of hirudin no effect on the APTT occurred. These results demonstrate that DDAVP infusion elevates factor VIII:C levels with an associated significant reduction in the anticoagulant effect of hirudin in vitro.
Subject(s)
Anticoagulants/antagonists & inhibitors , Deamino Arginine Vasopressin/pharmacology , Hirudins/analogs & derivatives , Factor VIII/drug effects , Hirudins/antagonists & inhibitors , Humans , In Vitro Techniques , Infusions, Intravenous , Partial Thromboplastin Time , Recombinant Proteins/antagonists & inhibitorsABSTRACT
The effects of the newly available biotechnology product, recombinant desulphatohirudin (CGP 39393) have been investigated in rats. This highly potent and selective thrombin inhibitor exhibited marked anticoagulant properties with controllable titration of anticoagulant effect, as measured by activated partial thromboplastin time (APTT), up to nearly four times control values. Furthermore, CGP 39393 exhibited impressive antithrombotic activity in vivo. In an arteriovenous shunt model of thrombus formation on a cotton-thread, the compound was capable of complete inhibition of thrombus development (ED50 = 0.3 mg/kg i.v. and 1.0 mg/kg s.c.). Venous stasis thrombosis was also highly susceptible to inhibition by CGP 39393 (ED50 = 0.01 mg/kg i.v. and 0.45 mg/kg s.c.). Comparison of the anticoagulant and antithrombotic activities of the compound shows that potent antithrombotic effects (83-97% inhibition in the rat shunt model) are achieved within the generally acceptable range of anticoagulation. These results suggest a clear potential for this new agent in the clinical treatment of thrombotic disease.
