Kinetics of the Anticoagulant Effect of Heparin

Abstract

The kinetics of heparin's anticoagulant activity were studied with four assay methods in human subjects, following single intravenous doses within the usual clinical dose range. The half-life of anticoagulant activity was about 1.5 hours. Minimum doses of heparin required to anticoagulate blood to a clinically desirable extent were about 35 units/kg. Of the four tests used, the whole-blood activated partial thromboplastin time provided the greatest precision, information, and economy, followed by, in order, the activated plasma partial thromboplastin time, the whole blood clotting time, and the partial thromboplastin time of plasma.