Pharmacokinetics and organ distribution in rats of a low molecular weight heparin.

Fluorescein-labelled low molecular weight heparin (OP/LMWH) pharmacokinetics and organ distribution were studied in the rat after intravenous administration at doses of 3 and 15 mg/kg. The pharmacokinetics of labelled OP/LMWH was dose-dependent like heparin, however, the anticoagulant activity such as anti-Xa was more prolonged. The rapidity of the disappearance of the fluorescence was quicker than the biological activity. The fluorescence was observed mainly in the liver and kidney as a diffuse aspect in the short time and as a globular aspect in the long time, mainly in Disse's space of the liver. These results confirm that the liver is important in the regulation of heparin metabolism and activity.