In May 2018 we suddenly found out that herbs containing the natural constituent arbutin, including Arctostaphylos uva-ursi (Bearberry) and Turnera diffusa (Damiana) had been restricted to prescription only Schedule 4 medicines by the Therapeutic Goods Administration (TGA). However the reasoning for such restriction was questionable, and so myself and Laura Dwyer – my research student – set out to determine if there was actually evidence that these herbs might be harmful. We just published the results of our review.
Arbutin is a glycoside of hydroquinone, which does have some concerns around its safety in oral preparations. However the key point is that the way the body handles arbutin after ingestion (i.e. its pharmacokinetics) vastly reduces the risk of harm from the hydroquinone which is eventually formed upon metabolism of arbutin. This is something which appeared to have not been initially considered by the TGA, and as a result a voluntary team of experts in various areas of herbal medicine was established to draft a proposal for changing the restriction. These experts included:
- Jason Rainforest
- David Casteleijn
- Diana Bowman
- Toby-Ann Pinder
- myself
Our first publication was in Advances in Integrative Medicine last year (2019), and discussed the key issues and the steps being taken to alter the regulatory status of arbutin-containing herbal medicines. You can read the full paper here:
Rainforest, J., Casteleijn, D., Bowman, D., Breakspear, I., & Pinder, T. A. (2019). Natural products regulation – Getting the balance right. The case of arbutin. Advances in Integrative Medicine, 6(3), 95–96. https://doi.org/10.1016/j.aimed.2019.01.006
Whilst this was occurring in the background, I decided to propose a research project where we would examine the literature around the safety of key arbutin-containing herbal medicines. Laura Dwyer, then a final year student, stepped up and we worked together over the next couple of years to examine the reports of harm in both clinical trials and published case reports for Arctostaphylos uva-ursi, Turnera diffusa, and Achillea millefolium (Yarrow).
Laura did an amazing job, with her preliminary data being exhibited as a research poster at the Naturopaths & Medical Herbalists of New Zealand 2019 Annual Conference, and now the final results have been published in the Australian Journal of Herbal & Naturopathic Medicine. If you are an NHAA member, you can read the full text for free:
Dwyer, L., & Breakspear, I. (2020). Systematic review of harm from case reports and clinical trials of the oral use of Arctostaphylos uva-ursi, Turnera diffusa and Achillea millefolium. Australian Journal of Herbal and Naturopathic Medicine, 32(4), 142–151. https://doi.org/10.33235/ajhnm.32.4.142-151
To cut a long story short, there was very limited evidence of harm in humans from the oral ingestion of these herbal medicines, certainly not sufficient to warrant restriction of these medicines.
Fortunately, as of 1 October 2020, all of our hard work paid off, and the Standard for the Uniform Scheduling of Medicines & Poisons was updated such that these herbs at their normal therapeutic dosages were no longer restricted. A very good outcome indeed, and shows that in many cases, given a well written and scientifically rigorous argument, the TGA is responsive to positive change.
Uva-ursi image by Jesse Taylor [CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)]
https://commons.wikimedia.org/wiki/File:Common_bearberry_(%22Kinnikinnick%22,_Arctostaphylos_uva-ursi)_-_fruits_and_leaves.JPG