Pharmacokinetics and Pharmacodynamics Assessment of Apixaban and Edoxaban in Patients with Child a or B Liver Cirrhosis

Patients with liver cirrhosis (LC) have a higher risk to develop venous thromboembolism (VTE), in particular portal vein thrombosis (PVT) and the risk is increased with advanced liver disease. Some studies have shown that anticoagulant therapy in patients with LC and PVT could improve their prognosis by reducing liver decompensation, variceal bleeding, encephalopathy, and portal hypertension complications. Direct oral anticoagulant drugs (DOAC) seem to be as effective and safe as traditional anticoagulant drugs [vitamin K antagonists (VKA) and low molecular weight heparins (LMWH)]. Moreover, some studies showed lower bleeding rate and more recanalization of PVT with DOAC than traditional anticoagulant drugs. However, physicians are still reluctant to anticoagulate this population. This is well illustrated by the lower rate of adequate prophylaxis during in-hospital treatment in LC compared to other patients. This is probably due to two reasons. First, the fear of inducing bleeding in patients with increased INR and persistent thrombocytopenia, although it has been shown that the VTE risk is independent of INR and thrombocytopenia. Second, there is still a large knowledge gap on the effects of the various anticoagulant drugs and on the best anticoagulant molecule to employ in this population. Indeed, both VKA and LMWH present several disadvantages in LC patients. VKA are not recommended because of unreliable INR (already increased at baseline) and the risk of pseudo-therapeutic INR values. As for LMWH, a non-negligible increase of bleeding complications has been observed in LC patients. It has been demonstrated that patients with LC exhibit a lower anti-Xa activity when treated with LMWH compared to other patients and that after spiking their plasma with a given amount of LMWH, the measured anti-Xa activity was lower than in plasma from healthy controls. Of note, the anti-Xa activity was corrected after supplementation of antithrombin. In case of anti-Xa monitoring, this could lead to LMWH overdosing. In fact, despite a lower anti-Xa activity, the anticoagulant effect of LMWH seems to be increased in LC patients when assessed by thrombin generation, possibly because of antithrombin-independent antithrombotic actions of LMWH. Therefore, also LMWH are not ideal for LC patients. Nevertheless, both VKA and LMWH are the anticoagulant most frequently administrated to patients with LC, possibly also because of limited data about DOAC. In fact, patients with advanced liver disease or "hepatic coagulopathies" have been excluded from clinical trials investigating DOAC.

DOAC (apixaban, rivaroxaban, edoxaban, and dabigatran) represent an alternative to VKA and LMWH with specific advantages, particularly the oral intake and a direct action on coagulation factors. Different studies showed similar to lower bleeding rates in cirrhotic patients on DOAC compared to cirrhotic patients treated with warfarin or heparins. This suggests that DOAC are possibly a safe and effective alternative to VKA and LMWH. However, before performing large randomised controlled trials, the effect of specific DOAC in LC should be further studied, to select the ideal molecule.