Use of antiplatelet agents in patients with atherosclerotic disease

VE-1902-A direct thrombin inhibitor with reversible covalent mechanism of action shows efficacy with reduced bleeding in rodent models of thrombosis

INTRODUCTION

High incidence of bleeding events remains a key risk for patients taking anticoagulants, especially those in need of long-term combination therapy with antiplatelet agents. As a consequence, patients may not receive clinically indicated combination antithrombotic therapy. Here, we report on VE-1902, a member of a novel class of precision oral anticoagulants (PROACs) that combines effective anticoagulation with reduced bleeding in preclinical testing.

METHODS AND RESULTS

Acting through covalent, reversible active-site modification of thrombin similar to a previously described molecule [1], VE-1902 shows potency and selectivity for thrombin inhibition in human plasma comparable to clinically relevant direct thrombin inhibitors (DTI) such as argatroban and dabigatran (thrombin generation assay ETP EC₅₀ = 1.3 μM compared to 0.36 μM and 0.31 μM for argatroban and dabigatran; >100-fold selectivity against related serine proteases). Unlike the current anticoagulants, VE-1902 does not significantly inhibit thrombin-mediated platelet activation in in vivo models of thrombosis. In the thrombin generation assay, the compound inhibits thrombin formation without significantly delaying the initiation phase of the clotting cascade. These features are possibly responsible for the observed reduced bleeding in tail bleeding and saphenous vein bleeding models. Consistent with this novel pharmacological profile, VE-1902 shows efficacious anticoagulation in several fibrin-driven animal models of thrombosis (arteriovenous shunt, venous stasis thrombosis, and thrombin-induced thromboembolism models), whereas it does not significantly prevent arterial occlusion in the platelet dependent FeCl₃ model.

CONCLUSIONS

By leaving platelet activation following vascular injury mostly unaffected, VE-1902, and the PROACs more generally, represent a new generation of precision anticoagulants with reduced bleeding risk.

Assessment of the prophylactic role of aspirin and/or clopidogrel on experimentally induced acute myocardial infarction in hypercholesterolemic rats

Introduction

Hyperlipidemia is a risk factor for cardiovascular diseases such as acute infarction. Inflammation and platelet activation are critical phenomena in acute myocardial infarction (AMI).

Aim

The aim of the study was to assess potential protective effects of aspirin and/or clopidogrel on AMI in hypercholesterolemic rats.

Methods

Forty adult male Wistar rats were divided into five groups (eight rats in each). Group I included normal healthy rats. The other 32 rats were subjected to induction of hypercholesterolemia by high-fat diet for 3 weeks, followed by induction of AMI by subcutaneous injections of isoproterenol (85 mg/kg/day, for 2 days). Rats were divided into the following groups: group II, rats with induced hypercholesterolemia and AMI; group III, hypercholesterolemic rats that received aspirin 30 mg/kg/day orally for 7 days before induction of AMI; group IV, hypercholesterolemic rats that received clopidogrel 10 mg/kg/day orally for 7 days before induction of AMI; and group V, hypercholesterolemic rats treated with both aspirin and clopidogrel in the same doses for 7 days before induction of AMI. Serum levels of pentraxin 3 (PTX3), transforming growth factor-β1 (TGF-β1), creatine kinase (CK), lactate dehydrogenase (LDH), total cholesterol and triglycerides were estimated in all rats.

Results

Isoproterenol-induced AMI in hypercholesterolemic rats was associated with an increase in serum levels of PTX3, TGF-β1, CK and LDH. Aspirin and/or clopidogrel pretreatment for 1 week led to a reduction of their levels as compared with non-treated rats. However, the reduction caused by combination of aspirin and clopidogrel was more than that caused by each drug separately.

Conclusion

Combination of aspirin and clopidogrel could be a therapeutic option for hypercholesterolemic patients to attenuate the complex vascular inflammatory process which is a key step in the setting of AMI.