Quality Issues of Herbal Medicines: Internal and External Factors

Certain herbal medicines, because of the complexity of their chemical content and the variety of bioactivities, can provide the poly-pharmacology that orthodox drugs cannot deliver. Natural products are rarely evaluated in the well-controlled clinical trials that are required to receive approval by regulatory bodies; therefore, they tend to have less scientific evidence to support their efficacy. However, all medicinal compounds are chemicals, whether synthesized in plants, animals, or in manufacturing laboratories, therefore, all medicinal chemical compounds should be held accountable to similar standards of quality (identity, purity, and stability), clinical effectiveness and safety; irrespective of their source, “If it is found to be reasonably safe and effective, it will be accepted” [3]. Reliable and consistent quality is the basis of efficacy and safety of herbal medicinal products. Given the nature of products of plant origin, which are highly variable and complex products with numerous biologically active components rarely completely identified, therapeutic results and safety issues vary greatly from product to product, even within a single class. Therefore, the evidence of both benefits and risks is specific to the product tested and cannot necessarily be extrapolated to other products, as is the case for synthetically derived compounds.