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

Abstract

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.

To prove the constant composition of herbal preparations, adequate analytical methods have to be applied (eg, photometric analysis, thin layer chromatography [TLC], high performance liquid chromatography [HPLC], and gas chromatography [GC]). Depending upon whether the active principle of the plant is known or not, different concepts (“normalization” vs. “standardization”) have to be applied in order to establish relevant criteria for uniformity.