The Quality Control of Herbal Medicinal Products

Where no pharmacopoeial monograph exists, manufacturers must supply their own comprehensive specification which should include the following  

Information on the site of collection, time of harvest, stage of growth, treatment during growth, drying and storage conditions. 

Tests for residues of pesticides, fumigants, radionuclides, heavy metals, other contaminants and likely adulterants. 

Assays for content of constituents of known therapeutic activity where these are not yet known with certainty, assays of marker substances must be used. All of these methods must be fully validated, using standard and accepted protocols for analytical method validation. 

This chapter attempts to explain why all these requirements are considered necessary 

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Unlike conventional pharmaceutical products, which are usually prepared from synthetic materials by means of reproducible manufacturing techniques and procedures, herbal medicinal products are prepared from material of plant origin which may be subject to contamination and deterioration, and may vary in composition and properties. Furthermore, in the manufacture and quality control of herbal medicinal product, procedures and techniques are often used which are substantially different from those employed for conventional pharmaceutical products. 

Personnel dealing with the production and quality control of herbal medicines should have adequate training in the specific issues relevant to herbal medicines. 

GACP, GMP and GLP standards. During the industrial manufacturing of herbal medicinal products not only the raw material is subject to rigid quality control, but also the quality of the semi-manufactured and finished product is monitored (in-process controls) and evaluated (end controls on content, identity, purity). Finally a pharmaceutical dosage form should comply with the applicable pharmacopoeial standards (e.g., crush strength of tablets, disintegration time of tablets and capsules, uniformity of mass and content [11-13]). 

Technical aspects of the contract should be drawn up by competent persons suitably knowledgeable on the specific characteristics of herbal medicines, including their production and quality control testing. 

The release of herbal medicines should be authorized by aperson who has been trained in the specific features of the processing and quality control of herbal materials, herbal preparations and finished herbal products. 

The identity and quality of herbal material, herbal preparations and of finished herbal products should be tested as described in the Quality control methods for medicinal plant materials (d). The minimum requirement for the technical equipment is for instruments to perform the tests described in (d). Moreover, each country should develop this basic requirement for technical equipment further, according to the country s needs. 

Few herbal medicinal products are on the market as authorised medicines in the EU, fulfilling the same stringent requirements that count for conventional medicinal products. This is largely due to the limited availability of randomised controlled trials to support the quality, safety and efficacy of herbal medicinal products. More often they are licensed as traditional herbal medicinal products, following an adapted and simplified registration wherein efficacy is made plausible based on available scientific data (well-established use) or long-term historic use in the EU (traditional use). Sufficient data to underpin the safety should be available in all cases and the quality of the herbal... 

Laasonen, M., Near-Infrared Spectroscopy, a Quality Control Tool for the Different Steps in the Manufacture of Herbal Medicinal Products, Dissertation Abstracts International, 64, 688 (2003). 

Official standards are absolutely necessary to ensure the quality, reliability, and homogeneity of herbal products for consumers. Standardized products are paramount to those in healthcare planning to conduct clinical research with these products. Independent laboratories and university-affiliated research reports have documented the considerable variation that exists in terms of quality and reliability in these products. Abroad, the ESCOP, composed of manufacturers of herbal medicines and herbal associations, is working with European research groups to develop quality-control standards for the production of natural products. This committee is developing monographs for incorporation into such references as the British Herbal Pharmacopoeia and the British Herbal Compendium. 

Qualification of critical equipment, process validation and change control are particularly important in the production of herbal medicines with unknown therapeutically active constituents. In this case, the reproducibility of the production process is the main means for ensuring consistency of quality, efficacy and safety between batches. 

The personnel of quality control units should have particular expertise in herbal medicinal products to be able to carry out identification tests, and check for adulteration, the presence of fungal growth or infestations, lack of uniformity in a consignment of medicinal plant materials, etc. 

Purity control of an herbal drug is not only relevant for the quality of a finished herbal medicinal product, but also for its safety. According to the Ph. Eur. herbal drugs are, as far as possible, free from impurities such as soU, dust, dirt and other contaminants such as fungal, insect and other animal contaminants and that they are not subject to decay. 

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