chieving
a high level of quality control for Kampo extracts presents the manufacturer
with a unique set of challenges. In the last issue of Kampo Today, we presented
an overview of the quality control process. This article, the second in
a series, focuses on the topic of quality control for raw herbs.The starting place for quality control of raw herbs is obtaining an adequate supply of the proper types of herbs needed for a given prescription. This is not as easy as it may seem, since many of the herbs used in Kampo have a large number of similar species, which without proper attention may be confused with the appropriate herb. Thus, careful attention must start at the locality where the herbs are grown or harvested to be sure that the appropriate species is being harvested.
Another important characteristic of the quality control process for raw herbs is the need to pay proper attention to the conditions under which the plant is grown. Plants grown in poor soil or with inadequate water may not develop sufficient amounts of the traditional active ingredients. In addition, only certain parts of different plants are appropriate for the preparation of Kampo prescriptions.
China serves as the preeminent source for the herbs used in Kampo medicines, supplying about 75% of the needs of Kampo manufacturers in Japan. In China, most herbs are gathered manually, and although there is a set of national guidelines, practice tends to vary from region to region. In order, therefore, to ensure that the proper raw herbal ingredients are being provided, it is necessary to have a detailed understanding of procedures and practices at the local level.
Beyond this, the Kampo Good Manufacturing Practice (GMP) standards set by Japan's Ministry of Health and Welfare and the Japan Kampo Medicine Manufacturers Association's self-imposed regulations further guide manufacturers of Kampo extracts in quality control. These regulations stipulate that the manufacturer must designate a crude drug control manager to sample, analyze and test raw materials to be sure that standards are met.
Tsumura has adopted its own more rigorous standards of quality control which go beyond the basic regulations. To begin with, ancient Kampo literature and classic monographs are studied to determine which species of an herb is most appropriate for a specific prescription, and where it occurs naturally. Since Tsumura endeavors as far as possible to use herbs that are grown in their native habitats, field research is often necessary. Thanks to its long history of activities in China, including academic exchange programs and various types of joint projects, the company has had ample opportunity to carry out such research in major herb-producing areas. And because plant buyers must negotiate with suppliers in the provinces where herbs are produced, Tsumura's network of commercial ties with Chinese traders at the provincial level is also critical.
The example of the ephedra herb, which is considered effective for treating fever and relieving pain, illustrates some of the complexities of raw herb quality control and how Tsumura approaches the process. About 40 species of ephedra occur throughout the world, 12 of them in China. Generally, three species are exported for herbal medicine use: Ephedra sinica, Ephedra intermedia, and Ephedra egiosetoma. These species vary slightly in color, diameter of stem, length of twig, number of leaves and shape of intersection.
Tsumura's plant specialists investigate the ephedra types separately, then conduct appearance, morphological and purity tests. Physicochemical property tests are also performed, focusing on species identification, purity, loss on drying, total ash, acid-insoluble ash, extract content, ingredient assay and essential oil content. Traditional sensory tests are performed involving the senses of sight, touch, taste, and smell. In the case of ephedra, the experienced eye and palate of the plant specialist play an indispensable role: ephedra herb is considered to be of good quality when the woody stem is minimal and its external color is slightly yellowish, when a reddish-purple substance is abundant in the center of the stem, and when it has an astringent slightly bitter taste that leaves the tongue a bit numb.
The lengthy, multifaceted process of ensuring that the raw herbs are properly selected and of good quality -- beginning in the fields and forests where they are grown and gathered -- is but the first step in the process of producing high quality herbal extracts for standardized prescriptions.