Effects of Standard Heparin and a Low Molecular Weight Heparin (Kabi 2165) on Fibrinolysis

Summary Previous and recent reports have suggested a fibrinolysisenhancing property of standard heparin and low molecular weight heparins, but these observations have never been confirmed in a study fulfilling appropriate methodological criteria. The aim of this study was to evaluate the effect of standard heparin and a low molecular weight heparin (Kabi 2165) on fibrinolysis in a randomized cross-over double blind placebo controlled study. Six healthy volunteers received intravenously a bolus dose of the following treatments: placebo; standard heparin, 5,000 I.U.; Kabi 2165, 5,000 anti-Xa U; Kabi 2165,10,000 anti-Xa U. Before the injection and at established times thereafter, blood samples were collected for the following assays in plasma: t-PA activity, PA inhibitor activity, fibrin plate lysis area (FPLA), plasminogen, α2-antiplasmin, fibrinogen and anti-Xa activity. Placebo and Kabi 2165, 5,000 anti-Xa U, had no effect on t-PA plasma level. Standard heparin and Kabi 2165, 10,000 anti-Xa U, produced a statistically significant increase in t-PA level at 1 hour after the infusion. This increase lasted for at least 1 hour after the infusion. No effect of any treatment on PA inhibitor, plasminogen, FLPA, α2-antiplasmin and fibrinogen was observed. We conclude that an intravenous bolus dose of both standard heparin, 5,000 I.U. and Kabi 2165, 10,000 anti-Xa U produces a delayed and sustained increase in plasma t-PA.