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PDR for Herbal Medicines.
by Jorg Gruenwald, T. Brendler, and C. Jaenicke, Sci. eds.: Medical Economics, Montvale, NJ. 1998. Not consecutively paginated. ISBN 1-56363-292-6. $59.95.

This book contains a great deal of useful information, but the format utilized makes access and understanding difficult, especially for its intended audience, physicians. The 600 or so botanical monographs are arranged alphabetically according to the genus and species of the Latin binomial. This means that most readers will have to waste time by looking at the index or referring elsewhere from a common-name text listing every time information on a specific herb is sought. It reminded me of the old descriptive pharmacognosy texts that organized drugs according to a taxonomic classification. The index pages of such volumes were always tattered and torn -- worn out by botanically deprived students.

Oddly enough, the genus designations and species epithets used as headings are both capitalized in Roman, not italic, type, and botanical authority citations are lacking. Then the principal common name follows below in italics. A reversal of this order (and type font) and reorganization based on the common names would have made the volume both typographically accurate and much more user friendly.

The monographs that follow begin with a "Description," which is often rather lengthy and of more interest to botanists than clinicians. This sometimes includes a very large number of so-called "Other [common] Names" of the plant, many of which are uncommon. Sections on "Action and Pharmacology" (including chemical constituents), "Indications and Usage," "Contraindications," "Precautions and Adverse Reactions," "Overdosage," "Dosage," and "Literature" follow. The references are usually secondary ones, mostly in the German language and, therefore, will probably not be consulted by most American physicians. They are not keyed to any specific statements in the text, rendering them even less useful.

The book is said to be based on the findings of the German Commission E, but one must read the "Foreword" to realize that the conclusions of that body are presented in an abbreviated "list" fashion (that is, preceded by square bullet points) under "Indications and Usage." These are often followed by traditional and folkloric uses that are generally not scientifically validated. A significant problem arises with herbs that failed to gain Commission E approval because such failure is nowhere referenced by the authors. For example, this volume notes, "Yohimbe bark is used for sexual disorders, as an aphrodisiac, and for feebleness and exhaustion." It also fails to mention any specific health hazards associated with proper use of the herb.

The Commission E monograph on the other hand, states "The therapeutic administration of yohimbe bark and its preparations is not recommended because of insufficient proof of efficacy and the unforeseeable correlation between risk and benefit."; It seems improper to quote Commission E findings when they are positive in nature but to omit them entirely when they are negative.

At first glance, this book would appear to contain 1,244 pages. Closer scrutiny reveals great gaps in pagination. Pages 47 to 100, 140 to 200, 228 to 300, and so on, are simply omitted.

Information in the monographs is often incomplete. Golden seal [sic] is said to act as an oxytoxic, mild laxative, antiinflammatory agent, vasoconstrictor, and hypertensive. Nothing is said about its misuse in this country in unsuccessful attempts to mask drug tests or about its purported utility as an immune stimulant. Nor is any statement made as to its nearly total lack of systemic effects following oral administration because its active constituents are so poorly absorbed from the gastrointestinal tract.

Another significant omission occurs with soy, which curiously enough, is said to derive from the wild type Glycine soya [sic] instead of the common cultigen Glycine max (L.) Merr. In that monograph, only the phospholipids are discussed as active constituents; the phytoestrogenic isoflavones that gave have gained signal importance in recent years are not mentioned.

A similar omission is found in the green tea monograph. The utility of that herb as an antioxidant is not discussed.

The volume also repeats some of the few conclusions of Commission E that have been found invalid. It repeats the warning that local application of capsicum should be limited to two days. We now know that capsicum creams containing low doses of capsaicin, which are approved drugs in the United States, must be used for much longer periods of time -- several weeks -- before they become effective.

In my opinion, the clinical utility of the PDR for Herbal Medicines could have been greatly improved by judicious editing. There are fewer than 100 herbs that are of major significance in this country. Of these, only a score or so have been proven effective by clinical trials, and less than a dozen account for well over 50 percent of the market. In a book intended to help M.D.s respond to their patients' needs, condensed factual information without critical evaluation of more than 600 herbs is overkill. One has difficulty finding a specific tree in the vast surrounding forest. Inclusion of such toxic herbs as jequirty, white bryony, European water hemlock, and groundsel is simply not justified. Nor do monographs on mouse ear, black nightshade, or frostwort add much to a clinical reference.

Why space should be devoted to these insignificant herbs while omitting such popular ones as cat's claw, cordyceps, ashwagandha, and red yeast is difficult to understand.

Because of the familiarity of physicians with the PDR name, this book will no doubt enjoy widespread sales. However, several other reference books in the English language currently offer more detailed information on the clinically significant herbs in a more readily accessible format than does this one. They also offer a far more critical evaluation of the data presented.

Science writer Isacc Asimov once wrote that he always refused to review books in his field by people who were simultaneously friends and rivals because it made objectivity difficult. "Will he [the reviewer] be trying to do a friend a favor or a rival an injury?" Although confident of his own integrity, Asimov saw no reason to put it to unnecessary tests.

I have just that problem with this review. However, there is no denying that the PDR for Herbal Medicines suffers from weaknesses in nomenclature, organization, data presentation, and interpretation, as well as coverage, which make it impossible to give it a favorable review. Many of these defects are the responsibility of the editor, not the authors. Dr. Gruenwald and his German colleagues would have been well advised to utilize the services of a knowledgeable American editor to assist them in developing a more pertinent, user-friendly reference for physicians in this country. As it now stands, the enumerated deficiencies detract appreciably from what could have been an effective compilation of useful herbal information.

[Reprinted with permission of the Lloyd Library and Museum from Lloydiana 1999: 4 (1):4-6.]

Following are the authors' comments to the review of Dr. Varro E. Tyler on the PDR for Herbal Medicines:

We appreciate Dr. Tyler's constructive critique of the new PDR for Herbal Medicines. Despite his self-avowed conflict of interest, we certainly do not question the integrity and objectivity of his remarks. Indeed, should he be interested in cooperating, we would welcome his participation in the development of future editions.

Nevertheless, we feel that it is a misunderstanding to judge PDR for Herbal Medicines as merely one more in the flood of books focused on current American fads in phytopharmaceuticals. Rather, the book is the major step in an ongoing effort to provide the entire healthcare community from physicians to toxicologists-with an unbiased, comprehensive source of information on all herbal remedies, both common and rare, therapeutic and toxic, potent and worthless. Its goal is to offer reliable answers on the broadest possible spectrum of internationally known botanicals, both popular and obscure, whenever a question occurs.

Just as Physicians' Desk Reference itself has grown over the years from a slim volume of some 300 pages to a compendium more than 3,000 pages in length, we expect PDR for Herbal Medicines to steadily improve and expand. For the second edition we are already addressing the few omissions noted by Dr. Tyler. We are also engaged in an ongoing review of the clinical literature that promises to significantly expand many of the existing monographs through inclusion of results of the latest well-designed studies.

PDR for Herbal Medicines calls attention to the findings of Commission E by presenting approved indications in bulleted lists. However, we would be remiss in omitting the many traditional uses (and misuses) to which an herb has been put in the past, since many healthcare practitioners may still be confronted by such practices. However, while including all such "folk" uses, we have been careful to note that insufficient evidence of their efficacy exists.

A discussion of nomenclature, indexing, and pagination would not appear to be fruitful. Suffice it to say that PDR for Herbal Medicines is modeled on the organization and structure employed in Physicians' Desk Reference, and arrangement that regular PDR users have found sensible, easy to use, and convenient.

Again, we thank our respected colleague, Dr. Varro Tyler, for his comments. Wherever possible and appropriate, we intend to implement his suggestions in a timely fashion.

Article copyright American Botanical Council.


By Varro E. Tyler