Vitamin K antagonists (VKAs) require close monitoring because of individual variations, drug-drug or food-drug interactions.1 Studies have shown that increasing a patient’s time in therapeutic range, as measured by their international normalized ratio (INR) value, maximizes the benefits of anticoagulation therapy and minimizes the risk of thromboembolic events.2-4 Therefore, keeping careful track of your patient's INR value to ensure it is in the optimal therapeutic range is critical.