About oral anticoagulants

Your doctor has prescribed for you a type of medicine called an oral anticoagulant, such as warfarin. These drugs are used to prevent the development of blood clots.

Vitamin K antagonists, have been used for over 60 years. Doctors are very familiar with their effects and safety profile. Despite newer drugs becoming available, many scientific studies and clinical experience show that VKAs are very effective in reducing the risk of stroke.

It is important to keep your blood’s clotting time within the range prescribed by your doctor. You may need to take your anticoagulant for a few weeks, months or even for the rest of your life. But no matter how long, your levels need to be regularly measured and that’s where INR self-testing is a great benefit.

But remember – you are far from being alone. There are over 6 million people worldwide taking long-term oral anticoagulants.

 

New Drugs

You may have heard about new oral anticoagulants on the market that do not require monitoring.

Recent studies have found:

  • At study sites with better INR control, incidence of major bleeding was similar for dabigatran 150 mg and warfarin1
  • Consistency in maintaining INR between 2.0–3.0 with warfarin will determine whether novel oral agents confer lower bleeding risk2
  • Low bleeding risk with dabigatran/factor Xa inhibitors3 will bring greater attention to importance of INR monitoring and dose-adjustment for those receiving warfarin

Evidence suggests that for patients with the following conditions, it is better to stay on warfarin treatment:

  • The patient has renal impairment5
  • The patient has a mechanical heart valve4
  • The patient is elderly (> 75 years)4
  • The patient has an increased risk of bleeding7
  • Cost is an issue7
  • The patients are children or adolescents7
  • The patient prefers a drug that has an antidote7
  • The patient is intolerant to the new drugs8
  • There is a risk of non-compliance4,5,6
  • There are co-morbidities (hypertension, heart failure, diabetes)6
References

Wallentin et al (2010). Lancet 376:975-983

  1. Cannon & Stecker (2010). Am J Manag Care 16:S291-S297
  2. Connolly et al (2009). N Engl J Med 36:1139-1151
  3. Available at: http://www.ukcpa.net/wp-content/uploads/2011/08/FINAL-UKCPA-Position-statement-on-NOACs-FINAL-July2011.pdf last accessed October 2011
  4. Wann et al (2011). J Am Coll Cardiol 57:1330-1337
  5. Fuster et al (2011). Circulation 123:269-367
  6. Market research with 288 GPs and 29 experts from Australia, Germany, UK, USA; Q2 2011
  7. Connolly et al (2009). N Engl J Med 361:1139-1151