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Introduction: EP217609 is a representative of a new class of synthetic parenteral anticoagulants with a dual mechanism of action. It combines in a single molecule a direct thrombin inhibitor and an indirect factor Xa inhibitor. EP217609 can be neutralized by a specific antidote avidin, which binds to the biotin moiety of EP217609., Purpose: The primary objective was to assess the neutralization of EP217609 by avidin in healthy subjects. Secondary objectives were to define the optimal avidin monomer/EP217609 molar ratio to achieve an adequate neutralization of EP217609 and to assess the safety and tolerability of EP217609 and avidin., Methods: Healthy subjects (n = 36) were randomized to a 3 by 3 replicated Latin square design between 3 EP217609 doses (4, 8, 12 mg) and 3 avidin monomer/EP217609 molar ratios (1:1; 2:1; 3:1). EP217609 was administered as a single intravenous bolus, and avidin as a 30-min intravenous infusion, starting 90 min after EP217609 administration., Results: Overall, EP217609 and avidin were well tolerated. One subject experienced a benign and transient typical pseudo-allergic reaction. The administration of EP217609 resulted in dose-dependent increases in pharmacodynamic markers. Avidin triggered a rapid and irreversible neutralization of EP217609 without rebound effect. Adequate neutralization of the anticoagulant activity was achieved with both 2:1 and 3:1 avidin monomer/EP217609 molar ratios. All safety parameters did not show any treatment-emergent clinically relevant changes or abnormalities in any dose group., Conclusions: These results will allow further investigation in patients requiring a neutralizable anticoagulant as those undergoing cardiac surgery., Study Registration: EudraCT number 2010-020216-10.

Unlabelled: EP217609 is a parenteral antithrombotic compound combining in one molecule an indirect anti-factor Xa inhibitor, a direct thrombin active site inhibitor and a biotin moiety., Aims: The aim of the study is to investigate the safety, pharmacokinetics and pharmacodynamics of single ascending intravenous doses of EP217609., Methods: In this randomised double-blind placebo-controlled study, healthy male subjects were administered intravenously single ascending doses (1, 3 or 10 mg) of EP217609 or placebo. Each treatment group consisted of 10 subjects of whom 8 received EP217609 and 2 received placebo., Results and Conclusions: All doses of EP217609 were well tolerated. A total of five treatment-emergent adverse events were reported, all considered unrelated, but no bleedings or other significant adverse events occurred during this study. In both plasma and urine, there was a strong correlation between EP217609 concentrations as measured by anti-factor IIa and Xa specific bioassays indicating that the two pharmacological activities of EP217609 did not dissociate in vivo. EP217609 pharmacokinetics were dose proportional and characterised by a low clearance, a small volume of distribution and a terminal half-life of 20.4 h. The long half-life was reflected in long-lasting, dose-dependent effects on activated and ecarin clotting time, thrombin and prothrombin time, activated partial thromboplastin time, thrombin generation time and anti-factor Xa activity. Pharmacokinetic/pharmacodynamic modelling indicated that the concentration of EP217609 producing 50 % of the pharmacodynamic effect was 3400 and 2210 ng/mL for activated clotting time and anti-factor Xa activity, respectively. These results warranted further clinical development of EP217609., What Is Already Known About This Subject: • There is a limited number of neutralisable anticoagulants, particularly when rapid neutralisation is required. • Synthetic anti-Xa compounds have predictable pharmacokinetic profiles. However, problems with thrombin rebound remain because of the inability to inhibit clot-bound thrombin., What This Study Adds: • This manuscript provides a comprehensive investigation of the pharmacokinetics, pharmacodynamics and safety of EP217609, and the results were the basis of future clinical studies in both healthy subjects and patients. • The pharmacokinetic/pharmacodynamic modelling provided information for dose selection in such future studies.

Efficient and safe anticoagulation is crucial in patients requiring percutaneous coronary intervention (PCI) or extracorporeal circulation during cardiac surgery. Although new anticoagulant strategies have emerged for PCI as alternatives to the established treatment with heparins, the development of new anticoagulants with an improved efficacy/safety ratio is still necessary. Our study compared the efficacy of the novel, dual-acting, neutralizable FIIa/FXa-inhibitor EP217609C101 (EP) at 2, 1.2, 0.9, and 0.6 μg/ml to unfractionated heparin (UFH), enoxaparin, and fondaparinux in preventing cardiac catheter thrombosis under in vitro conditions. Blood drawn by venepunction from healthy male volunteers (n = 10) pretreated with 500 mg aspirin orally was treated with the anticoagulant to test and continuously circulated through a cardiac catheter for 60 min or until the catheter became blocked by thrombotic debris. Anticoagulant efficacy was assessed by thrombus weight, electron microscopic features of the developing thrombi, and laboratory parameters. Whereas UFH, enoxaparin, EP 2, and EP 1.2 μg/ml secured maximum circulation times, statistically significant premature catheter occlusions were observed for EP 0.9, EP 0.6 μg/ml, and fondaparinux. The UFH group and both high-dose concentrations of EP showed significantly lower thrombus weights than the low-dose concentrations of EP and fondaparinux, (p ≤ 0.05). On electron microscopic analysis of the thrombotic debris no differences were observed in erythrocyte deposition between UFH, enoxaparin, and all EP concentrations tested. A significant reduction in fibrin deposition was achieved by UFH and EP 2 μg/ml but no significant differences in platelet deposition were found, except for a significant reduction for EP 0.6 μg/ml. Our in vitro study showed that EP217609C101 is a promising new drug that is dose-dependently superior to classical (UFH, enoxaparin) and newer (fondaparinux) drugs in preventing heart catheter thrombosis.