The Antithrombotic Activity and Pharmacokinetics of Enoxaparine, A Low Molecular Weight Heparin, In Humans Given Single Subcutaneous Doses of 20 to 80 mg

The pharmacokinetics of enoxaparine, a low molecular weight heparin, was randomly studied in 12 healthy male volunteers. Doses of 20, 40, 60, and 80 mg were injected subcutaneously in randomized cross-over fashion. Anti-IIa and anti-Xa activities (using amidolytic methods), and calcium thrombin time, were measured over 36 hours. The maximum Amax of the anti-IIa and anti-Xa activities appeared 3 to 4 hours after administration. The terminal half-lives of anti-IIa and anti-Xa activities were approximately 2 and 4 hours, respectively, with no significant variation between the different doses. For the anti-Xa activity, there was a highly significant positive correlation between the dose injected and individual values of Amax (r = +0.915; P less than .001) and AUC (r = +0.913; P less than .001). Enoxaparine displays a relatively small apparent volume of distribution (about 7.0 L) and its total body clearance is about 1.25 L/hr. The mean residence time ranges from 4.6 to 7.6 hours. Thus, the pharmacokinetic profile of enoxaparine is characterized by a linear relationship between dose and absorption, a relatively low clearance and long elimination half-life, and a high anti-Xa/anti-IIa ratio.