Prevention effect of orally active heparin derivative on deep vein thrombosis

The use of heparin as the most potent anticoagulant for the prevention of deep vein thrombosis and pulmonary embolism is nevertheless limited, because it is available to patients only by parenteral administration. Toward overcoming this limitation in the use of heparin, we have previously developed an orally active heparin-deoxycholic acid conjugate (LMWH-DOCA) in 10% DMSO formulation. The present study evaluates the anti-thrombogenic effect of this orally active LMWH-DOCA using a venous thrombosis animal model with Sprague-Dawley rats. When 5 mg/kg of LMWH-DOCA was orally administered in rats, the maximum anti-FXa activity in plasma was 0.35 +/- 0.02, and anti-FXa activity in plasma was maintained above 0.1 IU/ml [the minimum effective anti-FXa activity for the prevention of deep venous thrombosis (DVT) and pulmonary embolism (PE)] for five hours. LMWH-DOCA (5 mg/kg, 430 IU/kg) that was orally administered reduced the thrombus formation by 56.3 +/- 19.8%;on the other hand, subcutaneously administered enoxaparin (100 IU/kg) reduced the thrombus formation by 36.4 +/- 14.5%. Also, LMWH-DOCA was effectively neutralized by protamine that was used as an antidote. Therefore, orally active LMWH-DOCA could be proposed as a new drug that is effective for the longterm prevention of DVT and PE.