Is there a role for pharmacokinetic/pharmacodynamic-guided dosing for novel oral anticoagulants?

The novel direct oral anticoagulants (NOACs) represent a major advance in oral anticoagulant therapy and are replacing vitamin K antagonists as the preferred options for many indications. Given in fixed doses without routine laboratory monitoring, they have been shown to be at least as effective in reducing thromboembolic stroke as dose-adjusted warfarin in phase 3 randomized trials and less likely to cause hemorrhagic stroke. Pharmacokinetic and/or pharmacodynamic subanalyses of the major NOAC trials in patients with atrial fibrillation have established relationships between clinical characteristics, and drug levels and/or pharmacodynamic responses with both efficacy and safety. Based on these analyses, pharmaceutical manufacturers and regulatory authorities have provided contraindications and dosing recommendations based on clinical characteristics that are associated with drug levels and/or pharmacodynamic responses, stroke reduction, and bleeding risk to optimize the risk-benefit profile of the NOACs in the real world. The current fixed-dosing strategy of NOACs has triggered discussions about the potential value of laboratory monitoring and dose adjustment in customizing drug exposure to further improve the safety and efficacy of the NOACs in patients with atrial fibrillation. As there is neither high-quality evidence nor consensus about the potential role of laboratory monitoring and dose adjustment for the NOACs, a Cardiac Research Safety Consortium "Think Tank" meeting was held at the American College of Cardiology Heart House in December 2015 to discussions these issues. This manuscript reports on the deliberations and the conclusions reached at that meeting.