Anticoagulant effect of inositol hexasulfate as measurable by clotting times of fibrinogen and recalcified plasma.

Thrombin-clotting time of fibrinogen was delayed by inositol hexasulfate (IHS). Clotting time of the recalcified plasma was also delayed by IHS. Moreover, when IHS was intravenously injected into anesthetized male rabbits (0.11 mmoles/kg), it delayed clotting time of the recalcified plasma. IHS prevented generations of factor Xa and thrombin in the recalcified plasma. It is probable that IHS inhibits the clot-formation of the recalcified plasma in competition with calcium ions.