Understanding herbal medicine and liver toxicity. Authors reply

Prior to January 2004, nontraditional herbal medications were classified as food under the Food and Drug Act, which exempts Health Canada from providing any safety or efficacy data.[1] The Natural Health Products (NHPs) Regulations were then created to address Canadians’ concerns about the safety, efficacy, and manufacturing process of natural health products in Canada—a work still in progress.[2]

The fact that nontraditional medications, including herbal and traditional Chinese medicine preparations, are little regulated compared to traditional pharmaceutical medications is not a matter of debate. Not only is efficacy undocumented by clinical evidence, potential harm is underreported. In addition, there is minimal quality assurance in terms of manufacturing of these products, resulting in variable potency and potential mislabeling of active ingredients. Dr Carr seems unaware of the difference in the extent and rigor between Health Canada’s approval processes for drugs versus NHPs.

Prior to being approved for public consumption, a traditional medication is studied extensively in preclinical and clinical trials and is subject to tight surveillance post-public consumption to detail those rare side effects that might not have been apparent in the trials. In fact, many drugs have been pulled off the market at this stage. Lack of such standards is obvious when it comes to nontraditional medications. 

Dr Carr also raises the point that traditional medications are hepatotoxic, citing acetaminophen as an example. We are not disputing that traditional medications are associated with hepatotoxicity, or the fact that acetaminophen is responsible for most cases of acute liver injury (ALI)—although, invariably, most acetaminophen-induced ALIs are due to acute or chronic overdoses, and, in fact, acetaminophen is one of the safest analgesic medications if used appropriately. The point is missed that the hepatotoxic adverse effects of traditional medications are known and well documented, which allows physicians and pharmacists to monitor patients closely for any early signs of harm. 

Finally, Dr Carr questions, “Where did those two liver patients get their herbal products?” to which we answer, commercial traditional herbal clinics in Greater Vancouver!

Consumption of exogenous compounds, whether traditional pharmaceuticals or nontraditional medications, can induce acute liver injury. In the case of traditional medications, it is documented and monitored. In the case of nontraditional medications sold as food supplements, which are unregulated and unsupervised, it is unnoticed until it is too late.
—Trana Hussaini, PharmD
—Eric M. Yoshida, MD, MHSc, FRCPC
Liver Transplant Program, Vancouver General Hospital

References

1.    Health Canada. General questions – Regulation of natural health products. Accessed 18 December 2017. www.hc-sc.gc.ca/dhp-mps/prodnatur/faq/question_general-eng.php.
2.    Government of Canada. About natural health product regulation in Canada. Accessed 18 December 2017. www.canada.ca/en/health-canada/services/drugs-health-products/natural-no....