Abstract
In canada, the use of complementary and alternative medicine, specifically natural health products (NHPs), is significant. More than 70% of Canadians report regular NHP use and up to 31% of Canadians use three or more. 1,2 Such products are frequently used by patients with chronic or recurrent conditions; these patients are also the most likely to be prescribed conventional medications. 3 For example, 58% of patients taking narrow therapeutic index cardiovascular medications reported concurrent NHP use. 4 As the likelihood of an adverse event increases with the number of products used, patients who use prescription medications in combination with NHPs are potentially at greater risk for an adverse event than if they were using either product on its own. 5
Patients often use these “natural” therapies without the appropriate knowledge of how they may affect their underlying medical condition(s) and/or conventional medications. While many natural health products, such as echinacea, have a relative lack of serious adverse effects and drug interactions, others may be highly toxic and have significant effects on the absorption, distribution, metabolism, and excretion of conventional pharmaceuticals. Effective knowledge transfer to our patients about these potential concerns is vital in providing appropriate care.
A critical step toward providing patients with accurate information about natural health products is to change health care provider behaviour. In particular, pharmacists, physicians, and nurses need to routinely ask about NHP use as part of history-taking. Only a minority of patients spontaneously report such use to their conventional health care professionals, in part because they are concerned about how this information will be accepted. There is also widespread public perception that natural products are “safe” and therefore do not need to be disclosed. Since many patients are taking these products as part of self-care, health care professionals need to ask about NHP use and counsel patients with the best available safety and efficacy information. Although formal rigorous evaluation of these products has been fairly limited to date, research in this field is expanding rapidly.
Beginning in this issue, we will be writing a series of clinical letters on natural health products commonly used in Canada and purchased in community pharmacies. The focus of these articles will be on information about safety and potential drug interactions. Our goal is to assist community pharmacists in helping patients weigh the relative risks and benefits of starting or continuing with a natural health product. As over 65% of NHPs are purchased in community pharmacies, it is imperative that community pharmacists be aware of the issues involved with their use. 6 Unlike the staff in health food stores, pharmacists have access to accurate prescription information for patients purchasing NHPs as well as specific training in the pathophysiology of disease and pharmacotherapeutics. This affords community pharmacists an excellent opportunity to review their patient's medication profile, and identify potential concerns for discussion.
Fortunately, there are a number of reputable sources of information. Throughout this series, we will identify evidence-based resources for pharmacists to access. We hope this series will help remind pharmacists to ask patients about NHP use, side effects experienced, and potential drug interactions. Pharmacists are encouraged to report any adverse events or drug interactions with NHPs to Health Canada (www.hc-sc.gc.ca/dhp-mps/med-eff/report-declaration/form/ar-ei_form_e.html), as there continues to be a critical lack of information on this topic.
Community pharmacists can play a vital role in helping advance understanding about the nature and frequency of adverse events related to natural health products, and thereby improve the safety and well-being of Canadians. We hope this series will assist them in this endeavour.