A Note from WHO guidelines on good manufacturing practices (GMP) for herbal medicines

With the constant increase in the use of herbal medicines worldwide and the rapid expansion of the global market, the safety and quality of herbal materials and finished herbal products have become a major concern for health authorities, pharmaceutical industries and the public. The safety and efficacy of herbal medicines largely depend on their quality. Requirements and methods for quality control of finished herbal products, particularly for combining/mixing herbal products, are far more complex than for chemical drugs. The quality of finished herbal products is also influenced by the quality of the raw materials used.

The latest World Health Assembly resolution on traditional medicine (WHA56.31) requested WHO to provide technical support to develop methodology to monitor or ensure the quality, efficacy and safety of products. The quality of herbal medicines can directly affect their safety and efficacy. Member States face complicated technical issues in the quality control of herbal medicines. In order to promote and improve the quality of herbal medicines and also to reduce the proportion of adverse events attributable to the poor quality of herbal medicines, WHO has committed to the development of a series of technical guidelines related to quality assurance and control of herbal medicines, as well as to updating existing guidelines.

The manufacturing process is one of the key steps where quality control is required to ensure quality of medicinal products, including herbal medicines. Good manufacturing practices (GMP) is one of the most important tools for this measure.

The core requirements for GMP for herbal medicines are common to GMP for pharmaceutical products. In 1996, WHO issued “Good manufacturing practices: supplementary guidelines for the manufacture of herbal medicinal products”. However, at that time, not many Member States were considering GMP requirements for herbal medicines, and only key technical issues were presented. The increasing use of herbal medicines has led to further research on them and to the development of techniques for their quality control. In addition, more and more Member States have started to establish their own national GMP specific for herbal medicines. Therefore it became desirable for WHO to update the Good Manufacturing Practices (GMP) supplementary guidelines for manufacture of herbal medicines. These updated guidelines were finalized in 2005 and adopted by a WHO Expert Committee in 2006, leading to publication as annex 3 of WHO Technical Report Series, No. 937 (2006). In addition, WHO has also updated its core guidelines on GMP, which were published as annex 4 of WHO Technical Report Series, No. 908 (2003). As a whole, GMP control for herbal medicines needs to meet the technical requirements of both sets of guidelines. In order to consolidate the information and to make such technical guidance user-friendly, it was proposed to compile a WHO monograph on GMP for herbal medicines, which combines these two sets of technical guidelines. This will also serve as a key resource for technical training programmes in capacity building in herbal medicines.

The present consolidated guidelines include, “Core WHO GMP” and “WHO updated GMP: supplementary guidelines for manufacture of herbal medicines”, which are reproduced from the respective annexes of the WHO Technical Reports. This volume also contains the contents page of the “Quality Assurance Compendium Vol. 2, 2nd update (2007)”, a publication which includes all of the GMP texts published to date, in order to enable full cross-referencing to the WHO GMP, as the GMP guidelines on validation and water, in particular, might also be necessary to those manufacturing herbal medicines.

There is no doubt that GMP is a key step in ensuring the safety and efficacy of herbal medicines. However, meeting GMP requirements requires investment from manufacturers and this may be especially difficult for small manufacturers in developing countries. Investing in GMP may increase production costs, leading to an increase in the price of the final product. This will impact on the affordability of the medicines. Therefore, relevant national health authorities need to take this impact into consideration and take the appropriate measures to encourage and ensure that manufacturers are willing and able to improve their GMP. According to the experiences of some countries, giving a transition period to manufacturers for them to improve the GMP is one good example. Therefore, these guidelines are only a reference and the relevant national health authorities should, based on these guidelines, further develop their own GMP requirements according to their circumstances.