The commercially available non-vitamin K antagonist oral anticoagulants (NOAC) are an emerging therapeutic class, which includes dabigatran, rivaroxaban, apixaban, and edoxaban. Dose adjustment of the NOAC currently takes into account the presence of particular patient characteristics that may alter NOAC concentrations. These characteristics include the presence of renal impairment and concomitant drugs affecting proteins involved with the transport and metabolism of the NOAC. NOAC concentrations reflect anticoagulant activity; some studies have shown some correlation with the risks of adverse events, while others have not, and the association is debated by workers in the field. However, dose adjustment based on characteristics before dosing assumes that the patient has drug oral availability and clearance at the mean of patients with these characteristics. Direct quantification of NOAC concentrations, for example, through the use of calibrated coagulation assays, is likely to add further to individualization of dosing to the particular patient.
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