Although heparins are usually injected intravenously or subcutaneously, antithrombotic activity is observed in rat models following single oral heparin doses. Since repetitive dosing is usually needed for thromboprophylaxis, study objectives were to determine whether repetitive oral heparin prevented arterial thrombosis and to compare effectiveness to subcutaneous administration. Wistar rats were given subcutaneous or oral unfractionated heparin ([UFH] 1 mg/kg per 48 h), low-molecular-weight heparin ([LMWH] tinzaparin, 0.
View Article and Find Full Text PDFPurpose: Northern peoples can receive elevated radiation doses (1- 10 mSv/y) from transfer of polonium-210 (210Po) through the lichen-caribou-human food chain. Ingested 210Po is primarily blood-borne and thus many of its short range alpha particles irradiate the endothelial cells lining the blood vessels. The relative biological effectiveness (RBE) of alpha particles vs.
View Article and Find Full Text PDFAlthough heparin is not generally administered orally, the results of studies involving rats suggest that heparin is absorbed, with low levels in plasma but extensive distribution to the endothelium. To determine whether evidence of absorption after oral administration can also be demonstrated in human subjects, we administered unfractionated porcine heparin in a single dose of 1000 U/kg to 6 healthy human subjects. Plasma anticoagulant activity was monitored between 5 minutes and 72 hours after administration, and chemical heparin concentrations were determined in 24-hour urine samples for as long as 120 hours after administration.
View Article and Find Full Text PDFHeparins are antithrombotic drugs given by intravenous and subcutaneous routes. However, we have observed that heparins have antithrombotic activity in a rat model when administered orally despite low plasma levels, with low molecular weight heparins (LMWHs) being effective at lower single doses than unfractionated heparins (UFH). Since LMWHs may have other pharmaceutical uses and little is known regarding the pharmacokinetics of oral LMWHs, our objectives were to determine the distribution of the LMWH tinzaparin (Logiparin) following oral dosing.
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