Complementary and alterative medicine (CAM) is defined as any product, including herbal remedies/foods/teas, vitamins, minerals, and natural products, that can be purchased without a prescription at a health food store, supermarket, from a magazine/newspaper or online, for self-treatment.1
Taylor et al. evaluated CAM perceptions of emergency department patients in Australia. They determined 44% of patients felt that by using CAM they were “drug free,” with 29% of patients agreeing (or strongly agreeing) CAM use is always safe to take with prescription medications. In an earlier study, Eisenberg et al. evaluated CAM use perceptions in the United States and found 79% of patients felt that, combined with prescription drugs, CAM was superior to either modality alone.2 They also found 63% to 72% of CAM-using patients that had seen a medical doctor in the prior year did not disclose the therapy.
The two most common reasons cited by patients were “they felt it wasn’t important for the doctor to know (61%)” and “the doctor didn’t ask (60%).” Overall, national CAM-use surveys have revealed that about 80% of adults typically do not disclose CAM use to medical doctors.
It is, therefore, imperative that physicians ask patients about their CAM use. It also is important to remember there are more foods and beverages that contain some of these “natural” ingredients, and patients need to be queried about the use of these products. CAM products can complicate traditional patient management, either when used alone or in combination with prescription drugs.
A clinically significant drug interaction that bears its own warning is that of warfarin and chondroitin/glucosamine. Patients might not tell you that they are taking chondroitin/glucosamine, so you have to ask. Functional foods and beverages that include “natural” ingredients, such as glucosamine and chondroitin, and other CAM abound. Examples include Joint Juice (1,500 mg glucosamine), Vitamin Water, and others.3
Two case reports, and a report from the World Health Organization (WHO) Collaborating Center for International Drug Monitoring, and the MedWatch database point to a potentially serious drug interaction between glucosamine and warfarin.4-7 Although not FDA approved for joint supplementation, the usual daily dose should generally not exceed 1.5 grams of glucosamine and 1.2 grams of chondroitin. Chondroitin may have anti-coagulant activity, which would explain the increase in International Normalized Ratio (INR) seen in patients using it in combination with warfarin. The WHO database identified at least 34 cases of concomitant use, with most cases of increased INR resolving upon glucosamine discontinuation. Nine cases required physician intervention, and in one case a positive rechallenge was documented. In June 2007, there were 81 cases of a possible interaction from the MedWatch database, of these, 61 cases had potential alternate etiologies. Of the 20 possibly-related cases, five led to patient hospitalization due to bleeding complications; the median patient age was 62 years and there were no deaths reported.