Quality Criteria and Standardization of Phytopharmaceuticals: Can Acceptable Drug Standards Be Achieved?

Phytopharmaceuticals are composed of many constituents and are therefore very capable of variation. The variability of the plant material is due to different growth, harvest, drying, and storage conditions. Therefore, cultivation of the plants under standardized conditions is desirable. The polarity of the solvent, the mode of extraction, and the instability of constituents may also influence the composition and quality of the extracts and must therefore be kept constant. The quality criteria for herbal drugs are based on a clear scientific definition of the raw material. Depending on the type of preparation, sensoric features, moisture, ash, physical constants, solvent residues, and adulterations have to be checked to prove identity and purity. Microbiological contamination and foreign materials, such as heavy metals, pesticide residues, aflatoxins, and radioactivity are further criteria to be tested.