Welcome to Lesson 3 of this learning activity titled Medication Review, DOACS vs. Warfarin. The content in this lesson was developed by myself, Kate Malish, and I will also be narrating this lesson. Now that we have reviewed each individual oral anticoagulant, let's spend some time comparing them to see which patient population is best suited to Warfarin or a direct oral anticoagulant. As we have seen, Warfarin requires extensive monitoring of a patient's INR and therefore may require several dose adjustments to achieve the target anticoagulation. DOACS, conversely, require no routine lab monitoring other than periodic renal and hepatic tests. This is a major bonus to DOACS as it limits trips to the doctor and allows the patient to become familiar with their dosing regimen. Similarly to lab monitoring, Warfarin also requires consistency in a patient's diet, especially foods high in vitamin K. Something as simple as eating a salad one day for lunch rather than the patient's normal turkey sandwich may cause a reduction in INR. This is not an issue with DOACS, therefore patients have more freedom in foods they eat. Finally, DOACS offer a more simplified dosing regimen compared to Warfarin, which often requires changes to the patient's weekly dose. Patients on Warfarin often use a combination of several strengths which adds to their pill burden and may contribute to noncompliance. Although Warfarin has some obvious drawbacks, it is still the most commonly prescribed oral anticoagulant due to its breadth of indications and well-established protocol. While some patients may not like frequent office visits and lab monitoring, others get comfort in the transparency this monitoring provides. Warfarin allows patients to take an active role in their health care by controlling their diet and INR levels. It promotes a solid patient-provider relationship which many patients enjoy. While the DOACS can be used in almost every indication that Warfarin is used, there are two patient populations that Warfarin exclusively treats. Those are patients with a mechanical heart valve and patients with antiphospholipid syndrome, an autoimmune disease which can cause frequent clotting in arteries and veins and or miscarriages. For these patients, Warfarin is the only anticoagulant approved for use. Finally, Warfarin has a well-established reversal protocol which is easily accessed and readily available in health care settings. DOACS, by contrast, have only one approved reversal agent per individual drug which is not readily available and may be difficult to obtain. Idoxaban, as we reviewed, has no reversal agent which can be very detrimental. These are the key factors which determine which oral anticoagulant is best for the individual patient and should always be discussed between the patient and provider. Some other factors which may influence the patient and or provider's choice of oral anticoagulant are listed here. The onset of action becomes important when the need for anticoagulation is urgent or there is not time or ability for bridging the patient with IV anticoagulants. The half-life of the medication may be considered when a patient is not compliant with their medication regimen. A long half-life allows room for missed doses while a short half-life leaves little room for error. Patient adherence is very important with anticoagulants and a simplified dosing regimen is usually preferable. Comorbid conditions such as liver or renal impairment may also determine the choice of anticoagulant. Since the liver produces the body's clotting factors, Warfarin is usually contraindicated for patients with severe liver impairment. Conversely, patients with renal impairment may not be eligible for DOACs and Warfarin may be the best choice. Providers must also consider other medications the patient is taking and make informed decisions based on possible drug-drug interactions. As already discussed, patients with a mechanical heart valve or antiphospholipid syndrome must take Warfarin for anticoagulation. Finally, it is important to note that both Warfarin and DOACs are contraindicated in pregnancy. Women who are pregnant or plan to become pregnant should not take either class of medication. If there is a need for anticoagulation, low molecular weight heparin, known as Lovenox, is the drug of choice as it is pregnancy category B. Here is another helpful chart listing certain factors and the preferred anticoagulant. For your reference, LMWH stands for low molecular weight heparin, VKA stands for vitamin K antagonist or Warfarin, and UFH stands for unfractionated heparin. To round out this education on oral anticoagulants, I will discuss how to switch between anticoagulants if needed. When a patient is changing from Warfarin to a DOAC, they should discontinue Warfarin and begin dabigatran or apixaban once the INR is less than 2. They may begin rivaroxaban or edoxaban once the INR is less than 2.5. When a patient is changing from a DOAC to Warfarin, they should only discontinue the DOAC once their INR is therapeutic. To review, the target INR for most patients needing anticoagulation is 2 to 3. However, those with a mechanical heart valve need an INR of 2.5 to 3.5. To achieve this target INR, bridging with Lovenox may be needed before exclusively taking Warfarin. This concludes Lesson 3 of Medication Review, DOACs vs. Warfarin. Thank you for your participation.

DOACs

Warfarin

oral anticoagulant

INR levels

dietary restrictions