Safety of apixaban for venous thromboembolism prophylaxis: the evidence to date

Apixaban, a direct orally active anticoagulant (selective, direct factor Xa inhibitor) is approved for (primary) prevention of venous thromboembolism (VTE) in patients undergoing elective total-hip or total-knee arthroplasty, for acute treatment/prevention of recurrent events in patients with VTE, and extended prophylaxis in patients with a history of VTE. Another approved use is prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. The present overview focuses on the safety of apixaban specifically in the VTE setting. Apixaban displays favorable pharmacokinetic properties: simple twice-daily dosing, low inter- and intrasubject variability, dose and time linearity, and multiple elimination pathways not critically dependent on either renal or metabolic mechanisms. An extensive nonclinical program and the overall clinical development program (all approved and tested indications) provided no signal that would indicate any particular specific safety concern related to apixaban apart from the increased risk of bleeding. With regard to the approved VTE indications, safety (and efficacy) was assessed in five large pivotal Phase III trials. In comparison to currently recommended standard treatments, apixaban shows superior efficacy, while at the same time no excess risk of bleeding in patients undergoing total-hip or total-knee arthroplasty. In treatment of VTE, apixaban shows noninferior efficacy and a reduced risk of bleeding, whereas in extended prophylaxis it reduced the risk of VTE/VTE-related deaths, with no increased risk of relevant bleedings in comparison to placebo. Documented clinical experience with apixaban in daily practice is currently sparse. However, its use is progressively increasing, and there has been no signal so far that would materially change the perception of its safety profile as defined in the premarketing trials.