Complementary & Alternative Medicines (Part 2)

By: Alere Staff
Publication Date: Wed, 11/02/2011

Pharmacotherapy’s published study Warfarin-related Adverse Events Among Users of CAM (complementary and alternative medicines) confirmed the risk of non-prescription medicine use in patients taking warfarin.1

Non-prescription use is becoming more prevalent with natural medicines demonstrating the most dramatic growth of self-medication. Fluctuations in International Normalized Ratio (INR) test results, in otherwise stable patients, are more common as nutrition stores and internet sales of natural medicines skyrocket. Also increasing are the numbers of patients indicated and placed on warfarin for stroke prevention.

The attractions of natural medicines are many. The ease of obtaining and elaborate quality of life claims lure patients to take a natural medicine, often while taking warfarin and rarely reported.

The 16 week study conducted by Shalansky et. al forced the reporting of CAMs and evaluated their impact on elevations in INR values, bleeding events and general outcomes.

In the study population, all CAMs with the exception of salmon oil and vitamin E demonstrated a positive influence of bleeding events. “In the adjusted model, statistical significant associations between the use of several individual CAMs and bleeding events were identified: cayeene (OR 8.0, 95% CI 3.57-17.92), coenzyme Q10 (OR 3.91, 95% CI 2.09-7.31), ginger (OR 6.63, 95% CI 3.49-12.61), St. John’s Wort (OR 4.70, 95% CI 6.42-12.62). There was also a significant positive association between the use of two or more CAMs and a bleeding event (OR 2.11, 95% CI 1.07-4.16).”1

No individual CAM stood out as a significant risk for elevating INRs in the study group. At the same time investigators found no significant risk of Amiodarone as an agent that increased INR values. The lack of evidence of influence may be contributed to the tight control of the study group.1

Alcohol, while not a medicine, was found to be a risk factor for both bleeding and elevated INR test results. The study confirmed an increased bleeding risk in patients choosing: cayeene, ginger, willow bark, St. John’s Wort and coenzyme Q10.

While alternative medicines are stamped generally regarded as safe (GRAS), you should always discuss all medications and supplements with your doctor.

  1. Shalansky S, Lynd L, Richardson K, Ingaszewski A, Kerr C. Risk of warfarin-related bleeding events and supratherapeutic international normalized ratios associated with complementary and alternative medicine: a longitudinal analysis. Pharmacotherapy. 2007 Sep;27(9):1237-47.