Herbal medicine has become an increasingly popular health-care choice
and this growing trend has attracted the attention of the orthodox
medical community who consider herbs as pharmaceutical agents which need
to meet the safety and efficacy criteria that medical drugs are
expected to meet within the modern paradigm of evidence based medicine
(EBM).
From my own experience as a herbal practitioner and as an
officer in a professional association many herbalists I encounter seem
concerned about the potential of losing the traditional aspects of their
practice by having herbal medicine evaluated solely by EBM, and in
particular the reductionist philosophy at its centre which appears
ill-equipped to evaluate the holistic paradigm upon which traditional
herbalism rests. Consequently there is a growing tendency among herbalists to disregard
clinical research.
I would contend that this position is
untenable because although herbal medicine has 'worked' for centuries
without any such 'research' per se, the issue of herb-drug interactions
presents a case for reconsideration. I examine this issue within the
wider context of epistemological conflicts.
I suggest pause for
thought with the risks associated with herb-drug interactions out of
concern for patient safety. There is no experience within the herbal
tradition with herb-drug interactions upon which to draw until recently.
In reconsidering research from this perspective I have informed my
practice and developed a more mulch-perspective approach. This has led
me to consider what other types of research may be useful and
highlighted the need to consolidate perspectives as herbal medicine
moves into the 21st century.
Introduction
Herbal
medicines are becoming increasingly popular with demand increasing
exponentially in the last 20 years especially (Camber, 2007; Bent,
2008), while in developing nations some 80% of population still use
botanicals as their primary source of healthcare (World Health
Organization, 2008). This surge of interest in herbs has attracted
the attention of the scientific establishment and with the advent of
Evidence Based Medicine (EBM) as the dominant philosophy in modern
science there is a call for a thorough evaluation of herbal medicines
through controlled research. EBM has dominated clinical research since
the 1990's establishing published research as the true currency of
clinical decision making (Claridge & Fabian 2005; Hunt & Ernst,
2009). However the use of clinical research as a sole evidence base has
met with criticism. Sehon & Stanley (2003) have described this
definition of EBM as the gold standard of research as 'vacuous' and
'overly broad' and question the epistemological basis of such claims.
Proponents of EBM appear to reject other methodologies as if to suggest
there was no evidence behind them (Little, 2003).
In this article
I examine these various attitudes towards clinical research from the
perspective of a herbalist and I argue that while there are certainly
tensions between the scientific establishment and traditional herbalism
which need to be addressed, there can be a tendency among some
herbalists to dismiss the EBM model entirely. I will argue that this is
not a useful position to take, and using the example of herb-drug
interaction I suggest a re-examining of the herbalist approach to EBM.
In order to illustrate this point it will be necessary to examine what
underpins both herbal and medical paradigms and what has led to the
tension between them. I will then examine the area of herb-drug
interaction itself and point out the need, from both a safety
perspective and a drive for consilience (Wilson, 2001), to a
reconsideration of scientific research.
Herbal Medicine as an Evidence House
The
practice and art of traditional herbal medicine is based on the
employment of crude-herb extracts, such as tinctures, decoctions and
infusions (the practice), and their application to individual patients,
considered to have unique idiosyncrasies, via the consultation process
(the art). The practice and art of herbal medicine is informed by a
combination of ancient tradition, clinical observation and modern
research which form the foundation of an 'evidence house' with various
'rooms' (Jonas, 2001).
Herbalist practitioners contend that their
tradition is justified from a number of evidence bases, knowledge which
is gained from experience and in use since antiquity. Collectively
these various 'rooms' constitute an 'evidence house' (Jonas, 2001). EBM
tends to proceed from the perspective of reductionism employing a
hierarchy of evidence dominated by RCTs and consequently it may be
unsuitable as a measure for the holistic premise of herbal medicine; for
which a broader and more circular perspective is required (Walach et al. 2006). Evidence garnered
from multiple sources is appropriate to an understanding of holistic
medicine (Jonas, 2001; Walach et al. 2006). Below are the 'rooms' which
make up the evidence house of herbal medicine:
• Anthropological,
ethnobotanical and archeological evidence reveal the long use of plants
employed as medicines, dating back to the earliest civilizations.
•
These historical precedents have formed the bedrock of herbal traditions
for example, the Western Herbal Tradition (WHT) or Traditional Chinese
Medicine (TCM).
• Practitioners from these traditions have documented
their clinical experience in a series of herbals (the earliest known
source being the Shén Nóng Běn Cǎo Jīng, 2800 BCE) which have continued
to the present day and have become increasingly academic and
specialized.
• Herbals are based on botany, horticulture, pharmacy,
correspondences, oral tradition, philosophy and direct clinical
experience. They have become the basis of modern herbal training,
centered on the concepts of holism and vitalism.
• Clinical research
into herbal medicine began in the 1950's - some 40% of modern drugs are
based upon or derived from herbal medicines e.g. digoxin, morphine,
vinblastine and aspirin. Randomised controlled trials, systematic
reviews and research into phytochemistry, pharmacodynamics and
pharmacokinetics have become the bedrock of herbal EBM and have been
adopted by some herbalists as central to modern practice, but not by
all.
The above evidence bases, collectively considered, form the
foundation for the herbal medicine tradition from an epistemological
perspective however the scientific establishment argues that the EBM
model should be accepted as the only reliable evidence base for
identifying the safety, efficacy and effectiveness of herbal medicines;
or indeed as 'truth' while the rest are archaic, anecdotal or have
'haphazard ancient roots' (Ernst & Singh, 2008). EBM prefers to
model itself on best-evidence; knowledge gained from systematic reviews
of randomised controlled trials (RCTs) for example, and yet clinical
outcomes are multifactorial processes which cannot be isolated in a
controlled environment like the RCT. The real world of clinical practice
offers a window: while a single case history may be considered as
anecdotal a case series (10 or more cases) offers a basis for further
investigation (Fugh-Berman, 1996) and is a methodology which has been
neglected in epidemiological theory (Dekkers, Egger, Altman &
Vandenbroucke, 2012). Herbalists know what works and what doesn't
through experience.
Distrust of the Medical Paradigm: Where Does It Come From?
Practitioners
of Western Herbal medicine have a historical tendency to be cautious of
the orthodox medical fraternity in general. Antagonism between the two
philosophies has at times been especially strong such as in the wake of
the 1910 Flexner Report. This report by Abraham Flexner on the standards
of medical education across the United States at the time was the
result of a collaboration between a number of pharmaceutical companies
and the recently incorporated American Medical Association. Dominated by
science and pharmaceutical interests the report effectively put an end
to most herbal schools in North America (Haller, 1994) and instigated
the decline of the eclectic and physio-medicalist traditions which had
been the major influences in American herbal medicine for the previous
century (Treasure, 2005).
The physio-medicalist tradition was
introduced to the UK in 1838 by Albert Coffin (1798-1866) while the
concepts of the eclectics were imported by Wooster Beech (1794-1868) in
the 1850's - both became amalgamated within the British tradition and
the resulting groups formed the National Association of Medical
Herbalists in 1864. Brown (1985) quotes a UK government report on
unqualified medical practice in 1910 in which herbalists are tarnished: "A large number sell drugs for the purpose of procuring abortion, often at exorbitant prices".
Herbalism in England was significantly affected by a number of acts of
parliament from the Apothecaries Act of 1815 culminating in the Pharmacy
and Medicines Act of 1941 which more-or-less outlawed the practice
altogether while the professional herbal associations faced repeated
failure over any attempt for legitimation and recognition (Brown, 1985;
Church, 2009).
The 1941 Act was eventually replaced by the 1968
Medicines Act of which Section 12 and 56 (and subsequently
reincorporated in 2012 by the Human Medicines Act) gave a caveat to
herbal practitioners, however in more modern times European legislation
has created a period of legal uncertainty and transition. The
consequence of this historical tension has seen a tendency for some
herbalists to not only be cautious of EBM but to question if the entire
paradigm of modern clinical research is generally destructive to the
tradition.
These are just two historical examples of how
herbalists have come to be traditionally cautious of orthodox medicine
and yet this caution is not solely the reserve of herbalists. The
Thalidomide scandal of the late 1950's and early 1960's saw thousands of
birth defects in children whose mothers had consumed the pharmaceutical
drug Thalidomide. Since this
time similar instances have occurred in which medical drugs have had to
be withdrawn from the market because of serious side effects including
multiple fatality despite being extensively and rigorously trialed. In
2004 the pharmaceutical drug Vioxx
was withdrawn after it had been linked to an increase in cardiovascular
events (Rotthoff, 2010). Research into the controversial area of
iatrogenic deaths (deaths caused by inappropriate medication or surgery
for example) has shown that iatrogenesis is one of the leading causes of
death (Lazarou, Pomeranz, & Corey, 1998; Leape & Yessian 1999;
Null et al. 2006) while there is
growing evidence that trust in the medical establishment and
doctor/patient relationships have been eroded and issues of
accountability raised (Betz & O'Connell, 1983; Thomson, 2012). Issues
of bias within the pharmaceutical industry have also been examined
(Lexchin, 2012; Seife, 2012).
Deconstructing Holism
If
EBM can be said to be a modern paradigm then the holistic paradigm
which is central to herbal medicine theory is one which has endured for
thousands of years and has had to weather many storms. The term holism
was first coined by Smutts (1927) in his book Holism and Evolution
in which he describes 'wholeness' as an 'inherent character of the
universe' (Smutts, 1927). Yet the concept rides upon much more ancient
philosophies. An examination of the Ayurvedic tradition for example
discusses the notion that humans are made up of three attributes - the
physical, the subtle and the casual which can be extrapolated to imply
body, mind and spirit and any medical interventions must encompass all
of these attributes in order to treat the whole person (Gerson, 1993).
This approach stimulates the vitilistic principle, the body's innate
ability to self-heal.
By contrast the reductionist theory of EBM
prefers to bring explanations to a more simple level but it can be
argued that in so doing it avoids the fact that health is a morally
based enterprise with the reductionist approach pulling emphasis away
from the moral and towards the material (Little, 2003) evidenced by the
market-driven basis of the pharmaceutical industry and funding bias
(Chimonas et al. 2007).
Scott (1999) argues that holistic medicine in contrast can be seen as
'socially and politically progressive' (Scott, 1999).
Ernst and
Singh (2008) refer to early reductionist scientists in the 18th century
isolating active ingredients from plants so as to 'improve upon nature'.
They determine this methodology as scientific herbalism as opposed to
alternative herbalism which they condescendingly suggest rests on the
notion that 'Mother Nature knows best' (Ernst & Singh, 2008). They
imply that a religiosity or nature-superstition is inherent in holistic
traditions which is metaphysical and therefore incongruous as an
evidence-base. Their theory then rests on the principle that only plants
which have been investigated by EBM can be characterised as safe and
effective (Ernst & Singh, 2008).
In the holistic tradition
the use of whole herb extracts is central while in the reductionist
ethos the standardized active ingredient is employed as the agent of
research (a case of cutting the feet to fit the boots in this author's
eyes) and yet in discussing Hypericum perforatum
(St John's Wort) the same authors mention that attempts to isolate an
active agent (thought to be hypericin) proved to be not as effective a
therapeutic agent as the whole plant (Ernst & Singh, 2008). Ernst
& Singh's work has done much to alienate herbalists and other
alternative practitioners from the scientific model (Alderson, 2009).
The authors also commit the philosophical fallacy of confusing absence
of proof (lack of clinical evidence) with proof of absence (there is no
evidence) and in so doing encourage scientism. Holism offers a
multi-dimensional approach to healthcare which brings the patient
centre-stage whereas the reductionist perspective tends to see the
individual in terms of a disease or a statistic and in so doing
dehumanizes them (Little, 2003).
The EBM Model
In
EBM the safety, efficacy and effectiveness of a herb is largely
determined by the use of a single extract, thought to be the main
'active constituent' and which should be applicable in all cases as has
been discussed. Herbal extracts are standardised so the active
constituent is constant. This reductionist model, argue herbalists, does
not describe the synergy of the many active components found in a crude
extract, and so EBM is unsuitable as a methodology, or needs reworking
to take holistic principles into account.
Research takes several
lines of inquiry however. There is research to determine the collective
phytochemistry of a plant which may allow an evaluation of
pharmacological potential; there is research into pharmacodynamics (the
effect of the agent on the body) and pharmacokinetics (what the body
does with the agent); as well as research aimed at establishing whether
a herb is safe, whether it works and how effective it is but there is
also research into the interaction of herbs with modern drugs. To
dismiss all forms of research as merely the hegemony of scientism
however is to ignore the useful possibilities it may offer as herbal
medicine enters the 21st century. Some herbalists have considered that
drawing on and utilising the widest range of perspectives is a necessary
prerequisite to preserve the tradition itself (Conway, 2011).
Herb Drug Interactions
Modern
pharmaceutical drugs are a recent phenomenon and their origins can be
traced back to the development of aspirin in 1899. However these drugs
were not around when many of the great herbals were written and so there
are no points of reference in the herbal tradition to evaluate their
interaction with herbs until relatively recently.
Investigations into herb-drug interactions (HDIs) began from research in 1989 into the hypotensive drug Felodipine
in combination with alcohol. Grapefruit juice was used as a placebo as
part of the blinding process in the randomised controlled trial carried
out by Bailey, Malcolm, Arnold and Spence (1989) who made the novel
discovery that grapefruit had an inhibitory effect on the CYP450
pathways in the liver. This notable interaction created an interest in
the following decade and speculations began into HDIs as a consequence
(Dharmananda, 2000).
Despite the widespread use of herbs
documented HDIs are uncommon and yet in some situations they could have
serious clinical implications (Izzo & Ernst, 2001; Williamson, 2003).
Hypericum perforatum)
was one of the first herbs to be associated with HDIs. Some convincing
research into St John's Wort interaction with the drugs cyclosporine, digoxin and indinivar
has been established (Treasure, 2005). St John's Wort is now known to
act upon the Cytochrome P450 mixed oxidase system by decreasing plasma
concentrations in a significant way (Bauer, Stormer, Kerb, Johnne,
Brockmoller & Roots, 2002; Hojo, Echizenya, Ohkubo & Shimizu, 2011).
A period of scaremongering was in evidence however in which
poorly carried out research into HDIs appeared in peer-reviewed journals
and were subsequently quoted in secondary research papers without
critical examination of primary data, and continue to be quoted to this
day (Williamson, 2003; Treasure, 2005; Mills & Bone, 2005/2008). The
primary research suffered from issues of botanical identification,
adulteration, contamination, lack of phytochemical knowledge, glaring
inconsistencies or poor documentation for example (Fugh-Berman, 2000;
Mills & Bone, 2005/2008; Williamson, 2003). The publishing of flawed
data has done little to ingratiate herbalists. Issues of correct
procedure and documentation need to be rigorously and independently
examined in order to determine the difference between a theoretical or
an actual interaction. There is also a need to improve safety-related
search strategies in systematic reviews of the literature (Pilkington & Boshnakova, 2011)
One important issue here is when data is
used as a template for legislation. If primary data is flawed but used
as justification for legislation then we may suffer the consequences of
poor science becoming law.
Clinically significant interactions
have been reported for over 80 herbs (Ulbricht et al. 2008) but critical
examination of primary data does not seem to be in evidence. A review
by Ernst and Fugh-Berman (2001) determined that only 13% of the 108 HDI
cases they examined were classified as well-documented while 68% were
considered unevaluable (Fugh-Berman
& Ernst, 2001). Useful work has been done in differentiating
between actual, potential and theoretical HDIs however (Johns-Cupp,
1998; Brinker 1998/2001; Mills & Bone 2005/2008; Sarris &
Wardle, 2010; Stargrove, Treasure & McKee, 2008). Drugs with a low
therapeutic window are of general concern.
Although only a few
actual interactions have been observed it is important to stress the
unique idiosyncrasies of the individual which may increase risk factors
and the fact that new drugs will continue to appear on the market. There
is no time to be complacent in negotiating clinically significant risk
factors.
There has also been a tendency to focus on herb-drug
interactions from the negative perspective of adverse reactions and yet
positive interactions have also been noted. Etheridge (2012) cites
positive interactions between Coleus forskohlii and the asthma drug Salbutamol . Andrographis paniculata, Panax ginseng and Silybum marianum may reduce hepatic injury caused by alcohol while Withania somnifera may
reduce drug tolerance and dependence to offer further examples (Sarris
& Wardle, 2010). If herbs can also potentiate a drug then this may
mean that the patient might need a smaller dose and therefore a
reduction in side-effects and costs would be expected.
Rhetoric & Reality
This
data emphasises that it is incumbent upon the herbal practitioner to
appreciate the clinical implications of HDIs within their therapeutic
strategy and this in turn requires an appreciation of the need for
effective clinical research; but it also serves as pause for thought for
those who feel that research has nothing to offer the traditional
herbalist. The issue of safety and of 'do no harm' must be central to
clinical practice and in an age when the use of multiple medications is
common, concurrent use of herbs especially with drugs with a low
therapeutic window must be carefully evaluated.
To ignore
research in this regard is not only risky but arrogant. While it is
certainly true there are problems with research models (Little, 2003) it
becomes important for herbalists to be more directly involved in the
process in order to address those problems. A look at the history of
pharmacognosy in both Western Herbal Medicine and TCM reveals the
knowledge and interaction of plant constituents was well-known, indeed
modern medicine is based upon it (Dharmananda, 2000; Upton, 2011). There
is no reason why this research should not continue in regards of HDIs.
Conclusion
Differences
in philosophy between herbalists and the scientific establishment have
been ongoing and the resulting tension has alienated some herbalists
from research models. The development of phytotherapy, a type of
herbalism which tends to embrace EBM has resulted in tension within the
herbal community itself (Singer, 2007; Khoury, 2009). If an acceptance
of EBM can help ingratiate herbal medicine with the medical
establishment, for example as a means to legitimation, then at what
price? What happens to concepts such as holism within the process of
'mainstreaming'? Singer describes the potential of a 'bifurcation of
epistemology', a split between biomedically-informed and traditionally
orientated practitioners, the risk being that patients would lose choice
in approaches to their health care (Singer, 2007). By the same token
the isolation of traditional herbal medicine risks estrangement and
misunderstanding (Van Marie, 2002). A consilience of knowledge bases
appears the best strategy.
I have raised the issue of herb-drug
interaction as an important area in this context and examined the
reality behind it. The rhetorical slant that herbalists cannot associate
with anything which doesn't fit their paradigm risks stagnation on the
one hand but brings into question aspects of safety on the other. The
ongoing assessment of HDI risks presents an opportunity to look at how
research might benefit herbal medicine, and by extension those persons
who use it. While there are tensions between holist and reductionist
paradigms exploring knowledge from a variety of bases brings to bear
wider experience and multiple approaches to the clinical setting; yet it
is also incumbent upon herbalists to engage with the research process
and examine ways and means to make it more appropriate to the holistic
perspective.
No comments:
Post a Comment