RT Journal Article SR Electronic T1 Apixaban Metabolism and Pharmacokinetics after Oral Administration to Humans JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 74 OP 81 DO 10.1124/dmd.108.023143 VO 37 IS 1 A1 Nirmala Raghavan A1 Charles E. Frost A1 Zhigang Yu A1 Kan He A1 Haiying Zhang A1 W. Griffith Humphreys A1 Donald Pinto A1 Shiangyuan Chen A1 Samuel Bonacorsi A1 Pancras C. Wong A1 Donglu Zhang YR 2009 UL http://dmd.aspetjournals.org/content/37/1/74.abstract AB The metabolism and disposition of [14C]apixaban, an orally bioavailable, highly selective, and direct acting/reversible factor Xa inhibitor, was investigated in 10 healthy male subjects without (group 1, n = 6) and with bile collection (group 2, n = 4) after a single 20-mg oral dose. Urine, blood, and feces samples were collected from all subjects. Bile samples were also collected for 3 to 8 h after dosing from group 2 subjects. There were no serious adverse events or discontinuations due to adverse effects. In plasma, apixaban was the major circulating component and O-demethyl apixaban sulfate, a stable and water-soluble metabolite, was the significant metabolite. The exposure of apixaban (Cmax and area under the plasma concentration versus time curve) in subjects with bile collection was generally similar to that in subjects without bile collection. The administered dose was recovered in feces (group 1, 56.0%; group 2, 46.7%) and urine (group 1, 24.5%; group 2, 28.8%), with the parent drug representing approximately half of the recovered dose. Biliary excretion represented a minor elimination pathway (2.44% of the administered dose) from group 2 subjects within the limited collection period. Metabolic pathways identified for apixaban included O-demethylation, hydroxylation, and sulfation of hydroxylated O-demethyl apixaban. Thus, apixaban is an orally bioavailable inhibitor of factor Xa with elimination pathways that include metabolism and renal excretion. The American Society for Pharmacology and Experimental Therapeutics