Why I like Warfarin and Why You Should too

I am aware the love for Novel Oral Anticoagulants (NOACs) is growing and that warfarin is falling out of favour, especially in the setting of stroke prevention in atrial fibrillation or in the management of venous thromboembolism.  But hear me out on this one. Warfarin should stay and here’s why.

I am going to be blunt. Warfarin is a pain in the axx. With so many unique features such as long half-life, endless drug interactions and many factors to throw off the INR range, who wants to deal with warfarin? I have heard some hospitals have made it a mandate to switch everyone off warfarin (if clinically appropriate).

I get it. Who wants monitoring? Who wants to deal with an elevated INR result for a newly admitted patient when you know little about the patient, the medical history, the compliance history and everything else that may affect the INR result.

But learning how to manage warfarin has taught me how to be a better investigator, a better listener, a better problem solver and a better clinician overall.  Ultimately, it has taught me to treat everyone as unique individual and to personalize the dosing regimen accordingly. Has the patient missed few doses of warfarin? Or taken few extra unintentionally?  Any medication changes? Was the patient unwell recently? Diarrhea? Or has there been some changes with lifestyle such as travelling, increased exercise, smoking cessation or dietary changes.  Often when we spend the time to ask and investigate, we can identify many possible reasons for why the INR may be out of range and understand how to adjust (and not adjust) the dose accordingly.

These are important skill sets for any health care professionals.  Problems will not land in your hands with solutions all set out for you to dictate or execute. You need to dig and collect relevant information, assess the reliability of it, consider possible options and outcomes and make an informed decision accordingly. Isn’t most process for care provision follow this basic format?

By dismissing the option with warfarin quickly, we are teaching everyone to take the easy way, the quick way, not necessarily the best way or the most personalized way in medicine.  NOACs do offer the convenient advantage with no routine monitoring required and less drug interactions and other dietary considerations.  But less monitoring also means we may not be able to detect any bleeding concerns quickly enough, especially in the case of rapidly declining renal function.

At the end of the day, my conversation with patient or physician about which anticoagulatant to choose depends on the indication and the patient’s preference.  But we should not dismiss warfarin quickly and completely. It allows us to manage patients’ level of anticoagulation with precision, treating them like unique individuals which is what we should do all the time.

Here are some main reasons warfarin is still indicated or preferred over NOACs:

  • Patients with Mechanical Heart Valves
  • Patients with severe impaired renal function (CrCL below 30mL/min)
  • Patients on medications (e.g. Phenytoin) that interacts with NOACs (also interacts with warfarin but we can monitor with INR / phenytoin levels to manage the interaction)
  • Patients who cannot afford NOACs

Warfarin may not be able to compete with the NOACs anymore but we should not forget the lessons learned from this rat poison over many years of experience we have gained from it.

Thank you for reading my post.

 

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drugopinions

My name is Cynthia Leung and I am a practicing pharmacist in Kingston Ontario, Canada. This blog is for me to share my ideas, opinions and perspectives on how medications are used in our health care system. Note that these posts are my own opinions and do not represent the opinions of my current or former employers and / or organizations that I may belong to. Any possible case scenarios described in my posts would be modified to maintain patient confidentiality. This blog is not a platform for professional advise for patients or health care providers and the content is not meant to support any clinical decisions or replace professional opinions. Also the images are either taken or created by the author, or adapted with permission. I hope you will enjoy reading my posts!

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