Potential Interactions between Herbal Medicines and Conventional Drug Therapies Used by Older Adults Attending a Memory Clinic
Dergal J, Gold J, Laxer D, et al.
Objective
To evaluate the frequency of potential interactions between herbal medicines and conventional drug therapies in adults age 65 and older who attended a memory clinic.
Methods
It was hypothesized that herbal medicine use would be high among older adults attending the Toronto memory clinic because many herbal medicines target memory loss, depression, and insomnia. Adults 65 and older also often have other medical conditions for which they are taking multiple conventional drug therapies—making them vulnerable to an interaction.
Of the 217 patients attending the memory clinic, 195 consecutive patients (90%) participated in interviews. Prior to their interviews, they were called and asked to bring any herbal medicines, vitamins, and minerals as well as prescription and OTC drugs they were taking. During the interviews, almost all participants were accompanied by caregivers who confirmed information shared by patients and provided a background of patients' past use of herbal medicines and conventional drugs.
Results
Of the 195 patients, 33 (17%) were current herbal medicine users, 19 (10%) were past users who weren't taking them at the time of the interview, and 143 (73%) had never used them.
Of the 33 patients who were current users, the most commonly used herbal medicines were ginkgo (22 users), glucosamine sulfate (8), and garlic (6). In this group, 11 potential herb-drug interactions were identified: 8 ginkgo and aspirin (increases risk of bleeding); 1 ginkgo and trazodone (increases risk of coma); 1 ginseng and amlodipine (interferes with blood pressure medication); and 1 valerian and lorazepam (enhances sedative effects of benzodiazepines).
Conclusion
According to the authors, herbal medicines are widely used, and one-third of current users in the study were at risk for an herb-drug interaction. The most common potential interaction of this group, ginkgo and aspirin, is an important finding because both are regularly used by older people. Medical professionals need to be aware of potential herb-drug interactions and inform their patients accordingly.
Drugs Aging 2002;19(11):879-886.
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