Effects of heparin, dermatan sulfate and of their association on the inhibition of venous thrombosis growth in the rabbit.

This study compares the ability of unfractionated heparin, of dermatan sulfate, and of their simultaneous administration delivered as continuous intravenous infusion or as a single bolus injection to inhibit the growth of a standardized venous thrombosis in the rabbit. When delivered as continuous intravenous infusion for 4 h, heparin and dermatan sulfate inhibited thrombus growth in a dose dependent manner. The maximum antithrombotic effect of heparin was achieved at the dose of 0.15 mg kg-1 h-1 (25 U kg-1 h-1) which generated a mean plasma concentration of 1.8 micrograms ml-1 (0.31 U ml-1) and a 1.8 fold prolongation of the activated partial thromboplastin time (APTT) in comparison to the pretreatment value. A comparable antithrombotic effect was obtained with dermatan sulfate at the dose of 2 mg kg-1 h-1. This dose generated a mean plasma concentration of 30 micrograms ml-1 and a 1.3 fold APTT prolongation. Increasing these doses up to 10 fold did not improve the antithrombotic effect which did not overpass 60-70% of the controls. When the compounds were delivered simultaneously, the maximum antithrombotic effect (64%) was obtained with the following association: 0.06 mg kg-1 h-1 (10 U kg-1 h-1) for heparin and 1 mg kg-1 h-1 for dermatan sulfate. Increasing these doses up to 4 to 5 fold did not improve the antithrombotic effect. Heparin, dermatan sulfate and the association of both were also delivered as single bolus injections and the resultant antithrombotic effect was determined 4 h after saline infusion.(ABSTRACT TRUNCATED AT 250 WORDS)