Introduction

A Handbook of Herbal Medicines for the Practitioner and the Expert Patient

Herbal medicines are used increasingly in the United Kingdom, either alone or in addition to conventional treatment, which presents difficulties for the conventionally trained pharmacist, doctor, nurse, dentist, and so on. Herbal and nutritional products tend to be ignored by these practitioners, despite the fact that they are also used by some of these same professionals! It is important to be able to advise patients on the safe use of such products, including any possible interactions with prescribed or over-the-counter (OTC) medicines. However, although based on studies that are sparse, small and/or restricted to a particular setting, it can be concluded that generally health care professionals feel that their knowledge in this area is weak.

Doctors tend to know little about any aspect of herbal medicines, and often do not ask the patient if they are taking any (e.g. Lisk 2012), whereas pharmacists are more likely to answer correctly about the use of herbs, rather than about cautions, adverse effects, and interactions (e.g. Cuzzolin and Benoni 2009). Nurses also feel that their knowledge of herbal medicines is lacking (e.g. Temple et al. 2005) and in all surveys reported, respondents felt that health care professionals should know more, and that they themselves would benefit from training in this area. This book is an attempt to redress that lack of knowledge and provide useful practical information for the busy practitioner. It is intended to provide an overview of the most important medicinal and health food plants and products commonly used in the British Isles, including an assessment of the scientific evidence available for these ‘herbal medicines’. It is based on the premise that health care professionals must recognise patient and consumer demands for these products, regardless of their own personal opinions, and therefore be knowledgeable about them - especially as many are now regulated as medicines.

A recent concept in medical treatment is that of the ‘expert patient’: someone who usually has a long-term health condition but who is able to take more control over their health by understanding and managing the condition, leading to an improved quality of life. Many patients who wish to take herbal and nutritional supplements do their own research, often over the Internet, and so are at risk of receiving biased information by vested interests, or politically or philosophically motivated groups. The information given in this book is taken only from peer-reviewed resources and written in language that the expert patient can normally understand, in an attempt to provide an informative and safe resource for the patient, as well as the practitioner.

The introductory chapters are based on a series of articles by the authors in the Pharmaceutical Journal in 2012: 288:565-566; 288:627-628; 288: 685-686; 289:161-162; 289: 270-271.

Definitions, the market and the legal position

What are herbal medicines and who uses them?

Many people in the United Kingdom regularly use complementary and alternative medicine (CAM), either alone or in addition to conventional treatment. A recent systematic review has concluded that the average 1-year prevalence of use of CAM in the United Kingdom is >40% and the average lifetime prevalence >50%, with the most popular type being herbal medicine, at 29.5% (Posadzki et al. 2013). In 2003–2004, £3.25 bn was spent on herbal treatments alone in Western Europe (WHO 2008), and the global herbal supplements market is forecast to reach about £70 bn by the year 2017 (Global Industry Analysts 2013). These products are not only used by the ‘worried well’: a UK study found that 20% of cancer patients have used herbal medicines (Damery et al. 2011) and elsewhere, usage is even higher (see Williamson et al. 2013 for more details). Despite this, there generally is a lack of understanding of what herbal medicines actually are – or are not (IPSOS-MORI 2008).

Historically, plants have yielded many of our most important drugs, including morphine, taxol and digoxin, which are highly potent natural product – but not ‘herbal’ – medicines. Isolated compounds from plants are, in effect, identical as far as formulation, quality control and regulatory issues are concerned, to synthetic drugs or ‘single chemical entities’. Herbal medicines are different in that they are prepared from plant material, but with little or no chemical fractionation and thus contain a wide range of natural compounds, some of which are pharmacologically active, and some of which are not. They can be licensed in the same way as ‘conventional’ medicines (e.g. Senna alexandrina Mill. tablets, ispaghula husk preparations, capsaicin cream), and even regulated as controlled drugs (e.g. cannabis oromucosal spray; MHRA 2010) - but if so, they are not usually considered to be ‘herbal’ medicines. Most frequently, botanical ‘drugs’ are available as food supplements and herbal medicines (e.g. rhodiola and black cohosh preparations), and can be purchased from health food and general stores, as well as pharmacies.

CAM encompasses a wide range of therapies, based generally on philosophical and cultural traditions rather than clinical evidence, and may or may not have been investigated scientifically. Some herbal medicinal products (HMPs) are fully licensed (and therefore not part of CAM), whereas others are registered under the Traditional Herbal Registration (THR) scheme on the basis of traditional use only (see later). The licensed products, and even many of the THRs, have been demonstrated to be pharmacologically active medicines and should be treated as such by health care professionals, with all of the issues that entails. The regulatory framework of HMPs has, however, been interpreted in a variety of ways, and consequently some products remain unlicensed and are classified as ‘food supplements’.

UK regulation is largely based on European Union legislation, Directive 2001/83/EC, the European Traditional Herbal Medicinal Products Directive (THMPD) and the 1968 Medicines Act (Heinrich et al. 2012). Under this legislation, manufacturers of all products (including herbal remedies) classified as medicinal products must hold a marketing authorisation (MA, or product licence, PL) for that product, unless it satisfies the criteria for exemption from the requirement for an MA. In essence, medicinal products are defined by presentation (the purpose of the product), or by function (the actual effect of the product). All new chemical entities, including isolated constituents from plant and other natural sources, must have MAs for those products, based on the full dossier of chemical, pharmaceutical, pharmacological, toxicological and clinical data.

The legal position of herbal medicines in the United Kingdom:

Herbal medicines are classed as medicinal products by the MHRA (2012a). While globally between 40,000 and 50,000 plant species are used for medicinal purposes in both traditional and modern medical systems (Heywood 2011), only a few hundred are used more widely in the United Kingdom, other European countries, North America or Australia.

Herbal products are available on the UK market as:

• Licensed (herbal) medicines
• Traditional herbal medicinal products registered under the THMPD
• Herbal medicines exempt from licensing, which comprise three groups:
  1. Unlicensed herbal medicines supplied (and often made) by a practitioner following a one-to-one consultation
  2. Manufactured or imported herbal products for individual patients commissioned from a third party (‘specials’)
  3. Unprocessed, that is, dried and cut herbal medicines (produced by subjecting a plant or mixture of plants to drying, crushing, cutting or a simple process of extraction)
• Medical devices, that is, products used to diagnose, prevent, or treat disease, but without chemical effects on the body
• Products sold as food or dietary supplements, often over the Internet
• Prescription-only medicines (POMs): potentially hazardous plants may only be dispensed by order of a prescription by a registered doctor.
• Pharmacy-only medicines (P), supplied by a registered pharmacist; these may be subject to restrictions of dose (but not duration of treatment) and/or route of administration.

Terminology used for herbal medicines:

In addition to ‘herbal medicines’, the term ‘herbal medicinal products’ is also used, and highlights the commercial nature of these preparations. Less commonly, they may be called ‘phytopharmaceuticals’, ‘phytomedicines’, or even ‘traditional medicines’. In the United States, they are often referred to as ‘botanicals’; but in the United Kingdom, that also includes nutritional and cosmetic products. Similarly, a range of terms is also applied to foods with acclaimed health benefits: ‘food supplements’, ‘nutraceuticals’, ‘health foods’ or ‘medicinal foods’. In this book, we use the term ‘herbal medicines’ or ‘herbal medicinal products’ (HMPs) to describe those which have a clearly defined medicinal use, and ‘food...