Oral Corticosteroids & Warfarin
Corticosteroids are used to treat a variety of problems, including arthritis, asthma, skin conditions such as eczema and rashes, and autoimmune diseases such as lupus and multiple sclerosis. These steroids are similar to hormones that your adrenal glands produce to fight stress that is normally associated with illness and injuries. According to the National Institutes of Health, steroids can have strong side effects, including weakening of the bones and cataracts.
Interaction with warfarin?
A study published in the Annals of Pharmacotherapy found oral corticosteroids may interact with warfarin, but the documentation was limited. The study limitations included a lack of standardization of testing frequency.1
29 of the 32 (90%) patients experienced an increase in INR test results. Only 2 patients experienced a decrease in INR values during the study. The average increase was 1.24 (95% CI 0.86 to 1.62). The average INR change was seen 6.7 days after the first corticosteroid exposure. Half the patients experiencing an increase in test results required a change in their warfarin dosing. None of the study patients required hospitalization.1
Increasing testing frequency is recommended when making any changes to your diet, medication, etc. Studies have shown that increasing testing frequency with weekly testing of INR improves patient safety and helps keep the drug in its therapeutic effective zone.2,3 Weekly testing was shown to be the most effective testing frequency.2 Medicare and many private/commercial insurance reimburse patients for weekly patient self-testing.4 Go to the Getting Started page or call Alere at 1.800.504.4032 for more information about testing your INR at home.
- Hazlewood, Kathleen A., Fugate Susan E., Harrison Donald L. Effect of Oral Corticosteroids on Chronic Warfarin Therapy. Ann Pharmacother December 2006 vol. 40 no. 12 2101-2106.
- Am J Manag Care. 2014;20(3):202-209.
- Heneghan C., et al. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis. 2006. Lancet, 367, 404-11.
- Center for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management (CAG-00087R) [Memorandum]. 2008. Baltimore, MD.