As the article mentioned, McNeil Consumer Products Company, in partnership with Ashbury Biologicals, has recently entered the herbal-medicine area by marketing Tanacet 125, a feverfew preparation for the prevention of migraine.
The clearance of Tanacet 125 by the Drugs Directorate of Health Canada was based on clinical studies of its effectiveness for prophylaxis of migraine. However, there was a misunderstanding in the article, which stated that Tanacet needed a drug identification number (DIN) because its parthenolide content was beyond a level specified by the Health Protection Branch (HPB). This is not the case. The parthenolide level and dosage for Tanacet 125 are standardized to yield the same levels provided to the patients in the clinical studies that were reviewed by the Drugs Directorate.
A drug claim (and, hence, a DIN and specified labelling) is not permitted for any herbal product unless the Drugs Directorate is satisfied that the product is safe and effective for a particular indication. The product must also meet the consistency, standardization and other quality elements of Good Manufacturing Practices (GMP) required by the Food and Drug Regulations.
We appreciate the recognition given to manufacturers that persevere through the HPB requirements to obtain a DIN. Although some manufacturers may judge their projects to be mainstream herbal remedies, the recognized authority in Canada to validate drug claims and assure adherence to GMP is the Drugs Directorate. We value the level playing-field that this scrutiny encourages.
The Drugs Directorate has a more flexible approach to accepting claims than the article implies. Although Tanacet 125 was cleared on the basis of modern clinical studies, a variety of international traditional herbal references are also acceptable for the consideration of some other herbal drug claims. An update of the current requirements is provided by the Drugs Directorate.
The DIN review and approval process provided by the Drugs Directorate should be a minimum standard to determine the suitability of herbal products as therapeutic alternatives.
Hélène C. Carty
Director of Communications
McNeil Consumer Products Company
Guelph, Ont.
Kate Cottrell's article quotes Dr. William LaValley, chair of the Medical Society of Nova Scotia's Complementary Medicine Section, as stating that it is unreasonable that the same restrictions on newly developed conventional drugs should apply to "botanical products that have been in common usage without harm for centuries." Either Lavalley is misquoted or he is naïve.
Manufacturers of conventional drugs are required to list side effects that occur as infrequently as 1% to 2% of the time. Herbal preparations, distributed by practitioners with limited training in observation and consumed by those with even less, could be associated with toxicity at this or a greater frequency. Physicians are often hard-pressed to associate toxicity with a given therapy in the clinical situation. We depend on controlled trials to determine the associations, and we recognize that these too have their limitations when applied to the general population. How can herbal preparations distributed by lay people be assumed to be so safe? Toxicity induced by herbal preparations may be underreported because patients do not report that they are consuming herbal products when they present with a problem. Toxic reactions certainly occur.[1]
There are undoubtedly herbal preparations that have potential benefits. However, sometimes the therapeutic component is at suboptimal levels in the "raw product."[2,3] The lack of benefit of such raw products and the cost of consuming them in adequate therapeutic amounts need to be addressed more objectively.
I strongly support Dr. Anne Carter's position that herbal medications should be assessed in terms of outcome studies and quality-control standards. There are few enough research dollars. It is time for the purveyors and supporters of herbal preparations and other forms of alternative medicine to put their money where their mouth is. Set up research funds, invite grant proposals, have them reviewed for scientific merit and provide us with data.
Barry E. Koehler, MD, FRCPC
Clinical associate professor
Division of Rheumatology
Department of Medicine
University of British Columbia
Vancouver, BC
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