[Pharmacokinetics of an unfractionated heparin (Liquemin) in the dog after intravenous and subcutaneous application based on heparin activity].

In this study pharmacokinetic data for the unfractionated heparin Liquemin were obtained after intravenous and subcutaneous application. Each dosage was examined in 5 healthy, adult Beagle dogs. After intravenous application of 25, 50 and 100 I.U./kg body weight heparin plasma activity of 0.65 +/- 0.15 I.U./ml (mean +/- s), 0.91 +/- 0.10 I.U./ml and 1.94 +/- 0.22 I.U./ml was measured. Subcutaneous applications of 250, 500 or 750 I.U./kg revealed maximum plasma heparin activities of 0.25 +/- 0.10, 0.60 +/- 0.15 and 1.29 +/- 0.24 I.U./ml. The maximum heparin activity in the plasma was observed after 3.8 +/- 1.1 (250 und 500 I.E./kg) or 4.0 +/- 1.0 hours (750 I.E./kg), respectively. Intravenously applicated heparin has a short terminal half-life time (t50) between 22 and 44 minutes. The t50 after subcutaneous application of heparin was distinctly longer. After 250, 500 or 750 I.U./kg the t50 was 3.7 +/- 2.4, 3.5 +/- 1.2 or 5.3 +/- 2.4 hours. Corresponding to this result a lower total clearance (Cltot) was found with increasing doses. Especially the Cltot after subcutaneous injection decreased from 2.08 +/- 0.73 ml/min/kg (250 I.E./kg) to 0.83 +/- 0.27 ml/min/kg (750 I.E./kg). The volume of distribution of heparin corresponded approximately to the plasma volume. The total bioavailability of subcutaneously administered UFH was 53-100% depending on the dosage.