Short-term High-Dose Effect of Lovastatin on Thrombolysis by rt-PA in a Human Whole-Blood in vitro Clot Model

Abstract

High-dose hydroxymethylglutaryl coenzyme. A reductase inhibitor (statin) administration reduces neuronal injury and improves outcomes in experimental models of acute ischemic stroke, and has been shown to be safe in a phase 1 dose-escalation study using lovastatin at doses higher than currently approved for daily use. Statins also affect the hemostatic system by upregulating t-PA expression and decreasing plasminogen activator inhibitor (PAI-1) expression, platelet adhesion and thrombus formation in animal models. Since a thrombolytic agent, recombinant tissue plasminogen activator (rt-PA), is currently the only FDA-approved therapy for use in ischemic stroke patients, it is important to ascertain whether high statin doses impact the efficacy of rt-PA. The main goal of this study was to evaluate the effect of a high dose of lovastatin and its active form, lovastatin hydroxy acid, on rt-PA thrombolysis in an in vitro model. Percentage clot lysis was measured in the presence and absence of rt-PA in three different treatment groups: lovastatin, lovastatin hydroxy acid, and ethanol. The effect of ethanol on clot lysis was studied since ethanol was used to disperse the highly hydrophobic lovastatin. The decrease in clot width over time was measured using microscopic imaging of an in vitro human whole blood clot model; an approximately 400 μm diameter clot was formed on suture silk, suspended in human fresh frozen plasma (hFFP) and exposed to treatment. In the absence of rt-PA, clot lysis did not show statistically significant differences in the percentage clot lysis between different treatment groups (p=0.103). In the presence of rt-PA, clot lysis was greater than in the absence of rt-PA for all groups, but there were no statistically significant differences between treatment groups (p=0.385). In this in vitro study, high doses of lovastatin neither impaired nor enhanced the lytic efficacy of rt-PA.