The effects of the antiplatelet agents, aspirin and naproxen, on pharmacokinetics and pharmacodynamics of the anticoagulant edoxaban, a direct factor Xa inhibitor.

Edoxaban is an oral factor Xa (FXa) inhibitor in clinical development for stroke prevention in patients with atrial fibrillation, an elderly population that frequently receives aspirin (ASA) and/or nonsteroidal anti-inflammatory drugs for concurrent illnesses. Three studies were conducted to evaluate the pharmacokinetic and pharmacodynamic interactions of edoxaban 60 mg coadministered with low-dose (100 mg) ASA, high-dose (325 mg) ASA, or naproxen (500 mg) in healthy subjects (n = 126). Template bleeding times (BT) were measured. Mean baseline (predose) BT for the 3 studies ranged from 4.72 to 6.13 minutes. Edoxaban administered alone increased BT by 21%-35% (4 hours post dose) from baseline. Concomitant administration of edoxaban with high-dose ASA, low-dose ASA, or naproxen increased BT approximately 2-fold showing an additive effect greater than either agent administered alone. Edoxaban pharmacokinetics were not affected by concomitant low-dose ASA or naproxen, but high-dose ASA increased systemic exposure of edoxaban by approximately 30%. The effects of edoxaban on prothrombin time, activated partial thromboplastin time, international normalized ratio, anti-FXa, and intrinsic FXa activity were not influenced by administration with ASA or naproxen. Inhibition of platelet aggregation by high-dose ASA, low-dose ASA, or naproxen was not affected by edoxaban. Concomitant administration of edoxaban and ASA or naproxen was well tolerated.

Edoxaban administration following enoxaparin: a pharmacodynamic, pharmacokinetic, and tolerability assessment in human subjects.

Edoxaban is an oral direct factor (F)Xa inhibitor in advanced stages of clinical development. The primary objective of the present study was to assess the pharmacodynamics (PD) and safety of enoxaparin 1 mg/kg followed 12 hours (h) post-dose by edoxaban 60 mg, which is the regimen being used in the phase III study of edoxaban for the treatment of venous thromboembolism (Hokusai-VTE). This was a phase I, open-label, randomised, four-period, four-treatment cross-over study. Treatments were edoxaban alone (EDOX), enoxaparin alone (ENOX), edoxaban plus enoxaparin (EDOX+ENOX), and enoxaparin followed by edoxaban 12 h later (ENOX12-EDOX). Serial blood samples were collected for PD (thrombin generation, anti-FXa) and pharmacokinetic (PK) variables (edoxaban and its principal metabolite M4 by LC-MS/MS, and anti-FIIa as a surrogate of enoxaparin). The highest effect on thrombin AUC (endogenous thrombin potential, or ETP), thrombin (peak), thrombin generation lag time, and velocity index was observed for EDOX+ENOX, followed by ENOX, ENOX12-EDOX, and EDOX. The greatest effect on anti-FXa activity was observed for EDOX+ENOX, followed by ENOX12-EDOX. As expected, neither edoxaban nor enoxaparin significantly altered the PK of the other drug. There were no serious adverse events during the study. It is concluded that a 60-mg dose of edoxaban can be safely administered 12 h following enoxaparin 1 mg/kg.