The challenges in regulating traditional plant medicines in the era of contemporary evidence-based health policy
Thesis DisciplineHealth Sciences
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Traditional plant medicines are plant-derived therapeutic products prepared and applied according to long-standing medical customs. Around the world they are widely used in primary and preventative healthcare and readily available over the counter. Currently their position in New Zealand’s regulatory system of healthcare is not adequately addressed. This health policy possibly impacts access, user-information, and fails to safeguard public health. In its Traditional Medicine Strategy 2014-2023, the World Health Organization (WHO) calls on Member States to provide a regulatory framework so that the formal and safe contribution of traditional therapeutics in national systems of healthcare can be advanced.
The health policy question arising from this is how traditional plant medicines could be incorporated into a contemporary regulatory framework which is both evidence-based and appropriate for these long-standing therapeutic products. Evidence of effectiveness and safety of health interventions is paramount for regulatory integration of traditional plant medicines. Presumed lack of such evidence is one reason why New Zealand and other countries are yet to make progress in regulating these remedies.
The objective of this thesis is twofold. First, it is to establish whether systematic collation of long-standing empirical evidence from the clinical knowledge base on medicinal plants can provide reliable and verifiable pharmacological data. Can it be used to substantiate traditional health claims and therefore contribute to a framework for evidence-based health policies? This empirical evidence is informed by observations in patient care, evaluated and transmitted inter-generationally by clinical experts. In written medical traditions, therapeutic uses of medicinal plants are historically recorded in medical and more recently in specialised phytotherapeutic textbooks. Second, it is to determine if the way the EU dealt with evidence and safety requirements could help shape New Zealand’s policy on traditional plant medicines.
The research design of this interdisciplinary thesis spans across medical history, phytotherapy and health science. It employs a longitudinal, comparative textual analysis of European clinical textbooks from the early modern period onwards. It starts with the influential medical textbook New vollkommen Kräuter-Buch by the German physician, apothecary and botanist Tabernaemontanus (1522-1590) and concludes with present day teaching textbooks on phytotherapy. By way of exemplars it examines consistency and divergence of pharmacological data recorded on two medicinal plants, Arnica (Arnica montana) and St. John’s Wort (Hypericum perforatum) over 400 years. As a research instrument and to organise a large amount of historical and contemporary pharmacological records, the Historical Assessment Tool was developed and tested as a systematic and reproducible method. Traditional clinical knowledge is triangulated with information on the exemplars listed in the official Prussian and German pharmacopoeias and their commentaries, as well as with several modern regulatory and authoritative herbal monographs (i.e. by Commission E, EMA, WHO, ESCOP, and HagerROM). This bibliographic evidence is further compared with evidence of efficacy for indications as investigated with randomised-controlled trials (RCTs), and scientific evidence from experimental laboratory research.
Parallel findings of therapeutic indications on Arnica and St. John’s Wort across all qualitative and quantitative sources and time periods led to concluding that long-standing traditional clinical knowledge relating to the examined medicinal plants is a reliable and verifiable source of evidence. Evaluation of Arnica demonstrated an uninterrupted medical transmission of two clusters of indications over 400 years, relating to the treatment of consequences of injuries and accidents, and for pain related to the musculo-skeletal system and nerves. Analysis of data on St. John’s Wort showed congruency of medical transmission between three clusters of complaints relating, in modern terminology, to inflammation and catarrh of the gastro-intestinal system (gastro-enteritis, dyspeptic disorders), to burns and wounds, and to psychovegetative disorders (depressive moods, anxiety, nervous unrest, and hormonally driven dysphoria in relation to the female menstrual cycle). The validity of historical traditional indications was further supported when cross-checked with outcomes from clinical trials where undertaken. Data from experimental research provided insights into active constituents and possible mechanisms related to the empirically observed effects. The intergenerational professional literature on the materia medica represents the most comprehensive evidence source on the clinical scope of the medicinal plants investigated.
Notwithstanding the small number of exemplars analysed, clinically orientated historical and contemporary authoritative textbooks within the European materia medica are recommended as a comprehensive and reliable source of empirical evidence for substantiating traditional plant indications and clinically observed safety aspects. Empirical evidence is particularly important where modern scientific evidence is wanting or absent. The Historical Assessment Tool is proposed as a feasible method for the systematic collation and evaluation of bibliographic data for traditional health claims. This would be an additional pathway to make such data operational in an evidence-based policy framework.
The complexity of regulating traditional plant medicines is further illustrated by an inquiry into the European Union’s approach to dealing with evidence and safety requirements for such therapeutics. This thesis concludes with health policy recommendations arising from these analyses. These relate to the regulation of traditional plant medicines as a distinct therapeutic product category:
• to advance regulation on traditional plant medicine in New Zealand
• to implement a systematic framework for the collation and evaluation of bibliographic empirical evidence
• to develop a system for safety assessments that incorporates both historical safety observations and modern pharmacovigilance
• to create a practitioner-only sub-category alongside OTC remedies.