During the past decade, traditional systems of medicine have become a topic of global importance. Current estimates suggest that, in many developing countries, a large proportion of the population relies heavily on traditional practitioners and medicinal plants to meet primary health care needs. Although modern medicine may be available in these countries, herbal medicines (phytomedicines) have often maintained popularity for historical and cultural reasons. Concurrently, many people in developed countries have begun to turn to alternative or complementary therapies, including medicinal herbs.
Few plant species that provide medicinal herbs have been scientifically evaluated for their possible medical application. Safety and efficacy data are available for even fewer plants, their extracts and active ingredients, and the preparations containing them. Furthermore, in most countries the herbal medicines market is poorly regulated, and herbal products are often neither registered nor controlled. Assurance of the safety, quality, and efficacy of medicinal plants and herbal products has now become a key issue in industrialized and in developing countries. Both the general consumer and health-care professionals need up-to-date, authoritative information on the safety and efficacy of medicinal plants.
During the fourth International Conference of Drug Regulatory Authorities (ICDRA) held in Tokyo in 1986, WHO was requested to compile a list of medicinal plants and to establish international specifications for the most widely used medicinal plants and simple preparations. Guidelines for the assessment of herbal medicines were subsequently prepared by WHO and adopted by the sixth ICDRA in Ottawa, Canada, in 1991.1 As a result of ICDRA's recommendations and in response to requests from WHO's Member States for assistance in providing safe and effective herbal medicines for use in national health-care systems, WHO is now publishing this first volume of 28 monographs on selected medicinal plants; a second volume is in preparation.
1 Guidelines for the assessment of herbal medicines. In: Quality assurance of pharmaceuticals: a compendium of guidelines and related materials. Volume 1. Geneva, World Health Organization, 1997:31–37.
Preparation of the monographs
The medicinal plants featured in this volume were selected by an advisory group in Beijing in 1994. The plants selected are widely used and important in all WHO regions, and for each sufficient scientific information seemed available to substantiate safety and efficacy. The monographs were drafted by the WHO Collaborating Centre for Traditional Medicine at the University of Illinois at Chicago, United States of America. The content was obtained by a systematic review of scientific literature from 1975 until the end of 1995: review articles; bibliographies in review articles; many pharmacopoeias-the International, African, British, Chinese, Dutch, European, French, German, Hungarian, Indian, and Japanese; as well as many other reference books.
Draft monographs were widely distributed, and some 100 experts in more than 40 countries commented on them. Experts included members of WHO's Expert Advisory Panels on Traditional Medicine, on the International Pharmacopoeia and Pharmaceutical Preparations, and on Drug Evaluation and National Drug Policies; and the drug regulatory authorities of 16 countries.
A WHO Consultation on Selected Medicinal Plants was held in Munich, Germany, in 1996. Sixteen experts and drug regulatory authorities from Member States participated. Following extensive discussion, 28 of 31 draft monographs were approved. The monograph on one medicinal plant was rejected because of the plant's potential toxicity. Two others will be reconsidered when more definitive data are available. At the subsequent eighth ICDRA in Bahrain later in 1996, the 28 model monographs were further reviewed and endorsed, and Member States requested WHO to prepare additional model monographs.
Purpose and content of the monographs
The purpose of the monographs is to:
• provide scientific information on the safety, efficacy, and quality control/quality assurance of widely used medicinal plants, in order to facilitate their appropriate use in Member States;
• provide models to assist Member States in developing their own monographs or formularies for these or other herbal medicines; and
• facilitate information exchange among Member States.
Readers will include members of regulatory authorities, practitioners of orthodox and of traditional medicine, pharmacists, other health professionals, manufacturers of herbal products, and research scientists.
Each monograph contains two parts. The first part consists of pharmacopoeial summaries for quality assurance: botanical features, distribution, identity tests, purity requirements, chemical assays, and active or major chemical constituents. The second part summarizes clinical applications, pharmacology, contraindications, warnings, precautions, potential adverse reactions, and posology.
In each pharmacopoeial summary, the Definition section provides the Latin binomial pharmacopoeial name, the most important criterion in quality assurance. Latin pharmacopoeial synonyms and vernacular names, listed in the sections Synonyms and Selected vernacular names, are those names used in commerce or by local consumers. The monographs place outdated botanical nomenclature in the synonyms category, based on the International Rules of Nomenclature.
For example, Aloe barbadensis Mill. is actually Aloe vera (L.) Burm. Cassia acutifolia Delile and Cassia angustifolia Vahl., often treated in separate monographs, are now believed to be the same species, Cassia senna L. Matricaria chamomilla L., M. recutita L., and M. suaveolens L. have been used for many years as the botanical name for camomile. However, it is now agreed that the name Chamomilla recutita (L.) Rauschert is the legitimate name.
The vernacular names listed are a selection of names from individual countries worldwide, in particular from areas where the medicinal plant is in common use. The lists are not complete, but reflect the names appearing in the official monographs and reference books consulted during preparation of the WHO monographs and in the Natural Products Alert (NAPRALERT) database (a database of literature from around the world on ethnomedical, biological and chemical information on medicinal plants, fungi and marine organisms, located at the WHO Collaborating Centre for Traditional Medicine at the University of Illinois at Chicago).
A detailed botanical description (under Description) is intended for quality assurance at the stages of production and collection, whereas the detailed description of the drug material (under Plant material of interest) is for the same purpose at the manufacturing and commerce stages. Geographical distribution is not normally found in official compendia, but it is included here to provide additional quality assurance information.
General identity tests, Purity tests, and Chemical assays are all normal compendial components included under those headings in these monographs. Where purity tests do not specify accepted limits, those limits should be set in accordance with national requirements by the appropriate Member State authorities.
Each medicinal plant and the specific plant part used (the drug) contain active or major chemical constituents with a characteristic profile that can be used for chemical quality control and quality assurance. These constituents are described in the section Major chemical constituents.
The second part of each monograph begins with a list of Dosage forms and of Medicinal uses categorized as those uses supported by clinical data, those uses described in pharmacopoeias and in traditional systems of medicine, and those uses described in folk medicine, not yet supported by experimental or clinical data.
The first category includes medical indications that are well established in some countries and that have been validated by clinical studies documented in the world's scientific literature. The clinical trials may have been controlled, randomized, double-blind studies, open trials, or well-documented observations of therapeutic applications. Experts at the Munich Consultation agreed to include Folium and Fructus Sennae, Aloe, Rhizoma Rhei, and Herba Ephedrae in this category because they are widely used and their efficacy is well documented in the standard medical literature.
The second category includes medicinal uses that are well established in many countries and are included in official pharmacopoeias or national monographs. Well-established uses having a plausible pharmacological basis and supported by older studies that clearly need to be repeated are also included. The references cited provide additional information useful in evaluating specific herbal preparations. The uses described should be reviewed by local experts and health workers for their applicability in the local situation.
The third category refers to indications described in unofficial pharmacopoeias and other literature, and to traditional uses. The appropriateness of these uses could not be assessed, owing to a lack of scientific data to support the claims. The possible use of these remedies must be carefully considered in the light of therapeutic alternatives.
The final sections of each monograph cover Pharmacology (both experimental and clinical); Contraindications such as sensitivity or allergy; Warnings; Precautions, including discussion of drug interactions, carcinogenicity, teratogenicity and special groups such as children and nursing mothers; Adverse reactions; and Posology.
Use of the monographs
WHO encourages countries to provide safe and effective traditional remedies and practices in public and private health services.
This publication is not intended to replace official compendia such as pharmacopoeias, formularies, or legislative documents. The monographs are intended primarily to promote harmonization in the use of herbal medicines with respect to levels of safety, efficacy, and quality control. These aspects of herbal medicines depend greatly on how the individual dosage form is prepared. For this reason, local regulatory authorities, experts, and health workers, as well as the scientific literature, should be consulted to determine whether a specific herbal preparation is appropriate for use in primary health care.
The monographs will be supplemented and updated periodically as new information appears in the literature, and additional monographs will be prepared. WHO would be pleased to receive comments and suggestions, to this end, from readers of the monographs.
Finally, I should like to express our appreciation of the support provided for the development of the monographs by Dr H. Nakajima and Dr F. S. Antezana during their time as Director-General and Assistant Director-General, respectively, of WHO.
Dr Xiaorui Zhang
World Health Organization