For years, warfarin has been the favored treatment for venous thromboembolism and the prevention of stroke in patients with atrial fibrillation, but today, new oral anticoagulants (NOACs) have emerged as an alternative to warfarin, exhibiting significant efficacy in comparison, as well as reduced cases of intracranial hemorrhage. Warfarin treatment requires following algorithms for dose adjustment, and constant monitoring is necessary. Warfarin often requires bridging therapy, especially in high-risk patients or in those with continued subtherapeutic international normalized ratios (INRs). It has multiple food and drug interactions that can interfere with the desired anticoagulant effect, and can make it difficult for patients to adhere to their therapy.
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Due to these suboptimal factors, NOACs are desirable as options for patients who need long-term anticoagulation therapy. Before prescribing them, it is important to become familiarized with the pharmacological characteristics and metabolism of the therapies in order to be able to carefully explain to patients their benefits and adverse reactions, and emphasize how poor adherence could be fatal due to potential adverse events such as a pulmonary embolism.
Among the advantages of NOACs are the following features:
- Available in fixed doses
- Bridging not required
- More predictable
- No intense laboratory monitoring
- Rapid onset of action
- Less food and drug interactions
Conversely, there are disadvantages for NOACs as well. Accurate monitoring in cases of suspected toxicity is lacking. Although there are some antidotes undergoing clinical development, none are currently available. NOACs cannot be administered in patients who have a mechanical prosthetic heart valve. For patients with end-stage renal disease, careful monitoring must be in place.
While they do not require the more rigorous monitoring as is typical with warfarin, periodic checks are advisable. Monitor for bleeding, GI adverse reactions, hypersensitivity reactions, and other adverse events. Periodically monitor renal function as clinically indicated. When necessary, monitor anticoagulant activity by using activated PTT or ecarin clotting time, and not INR. Frequently monitor for signs/symptoms of neurological impairment in patients who are receiving neuraxial anesthesia or undergoing spinal puncture. Monitor for thrombotic events in patients discontinuing therapy.
In order for effectiveness and safety, patient compliance to treatment is essential. Instruct to take exactly as prescribed and not to discontinue without discussion. Inform patients that bleeding may occur more easily and may last longer. Instruct them to seek medical care if any signs/symptoms of bleeding, dyspepsia, or gastritis occur. Advise patients who have had neuraxial anesthesia or spinal puncture to watch for signs and symptoms of spinal/epidural hematoma, especially if they are taking NSAIDs or platelet inhibitors concomitantly. Instruct patients to inform any other healthcare provider that they are taking an NOAC before they schedule an invasive procedure (including dental procedures). Inquire if the patient is nursing/pregnant or intending to nurse or become pregnant. Instruct pregnant women receiving therapy to report any bleeding or symptoms of blood loss immediately.
NOACs available today are the recently FDA-approved Pradaxa (dabigatran), Xarelto (rivaroxaban), Eliquis (apixaban), and Savaysa (edoxaban). Keep informed on these and thousands of other available products by using PDR.net as a resource. Stay current on alerts and specific product labeling by providing updated contact information. To have updated drug information, full labeling, and safety warnings integrated into your electronic prescribing system automatically, and at no cost to you, be sure to request PDR drug data feeds, including PDR BRIEF.
Salvatore Volpe, MD, FAAP, FACP, CHCQM
Chief Medical Officer