Traditional anticoagulants such as warfarin and enoxaparin have several limitations including

Traditional anticoagulants such as warfarin and enoxaparin have several limitations including parenteral administration need for laboratory monitoring and ongoing dose adjustment which may limit optimal patient care. deep vein thrombosis (DVT) and pulmonary embolism (PE). Although the exact incidence of VTE is not known it is estimated to affect 900 0 patients each year in the United States [1]. Approximately one-third of these cases are fatal pulmonary emboli and the remaining two-thirds are nonfatal episodes of symptomatic DVT or PE [1]. VTE is the second most common cause of extended hospital stay and the third most common cause of in-hospital mortality [2]. Because it causes considerable morbidity and mortality VTE places a substantial burden on healthcare resources [3 4 Without thromboprophylaxis the incidence of hospital-acquired DVT based on objective diagnostic screening is 10-40% among medical or general surgical patients and 40-60% among patients who have undergone major orthopedic surgery such as total knee replacement (-)-Epicatechin gallate (TKR) total hip replacement (THR) and hip fracture surgery [5]. Patients with cancer are at a greater risk of new or recurrent VTE than patients without (-)-Epicatechin gallate cancer. VTE risk is 3- to 5-fold higher in cancer patients who are undergoing surgery and 6.5-fold higher in cancer patients receiving chemotherapy than in patients who do not have cancer [6 7 The efficacy of traditional anticoagulants in preventing VTE in patients undergoing major orthopedic (-)-Epicatechin gallate surgery and in hospitalized acutely ill medical patients is well established [5 8 However these agents have several limitations that may limit optimal patient care such as their parenteral administration need for laboratory monitoring and ongoing dose adjustment (Table 1) [12-16]. Newer oral anticoagulants such as direct thrombin inhibitors (e.g. dabigatran etexilate) and direct factor Xa inhibitors (e.g. rivaroxaban apixaban and edoxaban) have been developed to overcome these drawbacks and thereby improve patient care. Their pharmacologic targets in the coagulation cascade are described in Figure 1 and their general pharmacologic characteristics are summarized in Table 2. The objective of this paper is to provide (-)-Epicatechin gallate an overview of the available clinical trial data for these new oral anticoagulants from the perspective of prevention and treatment of VTE and to provide a practical update for clinicians. Figure 1 Site of action of new oral anticoagulants in the coagulation cascade. Table 1 Limitations (-)-Epicatechin gallate of traditional anticoagulants. Table 2 Pharmacologic profiles of new oral anticoagulants in clinical use. SHFM6 2 Direct Thrombin Inhibitors Thrombin is the final mediator in the coagulation cascade that facilitates the conversion of fibrinogen to fibrin (Figure 1). Thrombin also activates factor V factor VIII and platelet-bound factor XI which generate additional thrombin [17]. Moreover thrombin is a potent activator of platelets [17 18 Direct thrombin inhibitors inactivate fibrin-bound thrombin which is an important trigger of thrombus expansion and also directly inactivate free thrombin [19]. 2.1 Dabigatran Etexilate 2.1 Pharmacology Dabigatran is a potent competitive reversible thrombin inhibitor that binds directly to the active binding site of free or fibrin-bound thrombin in a concentration-dependent manner [20 21 After oral administration dabigatran etexilate is absorbed via the gastrointestinal tract and rapidly hydrolyzed by nonspecific esterases in the gut plasma and liver to its active (-)-Epicatechin gallate form dabigatran [21]. Peak plasma concentration is achieved 0.5-2 hours after administration of the drug [22]. It has a half-life of 12-17 hours [20] an absolute bioavailability of 3-7% and approximately 35% plasma protein binding [23]. Approximately 80% of dabigatran is excreted by the kidneys [24]. Dabigatran etexilate but not dabigatran is a substrate of P-glycoprotein (P-gp) an intestinal drug transporter and its absorption is influenced by a number of P-gp inhibitors and inducers. Neither dabigatran etexilate nor dabigatran is metabolized by the cytochrome P450 system. In addition dabigatran does not seem to inhibit or induce cytochrome P450 enzyme activity. Dabigatran induces dose-proportional and near-linear increases in activated partial thromboplastin time (aPTT) prothrombin time (PT) thrombin time (TT) and ecarin.