Abstract: The significance and indispensability of stability testing in development of dosage forms/formulation is well recognized in the pharmaceutical industry. Stability testing is necessary to ensure the product is of acceptable quality throughout its entire storage period. An important part of quality control of herbal products is the evaluation of the chemical stability of a finished product during the storage period. Measuring chemical stability is very challenging task due to the complexity of a plant extract, which may contain thousands of different compounds. The purpose of stability testing is to provide evidence on how the quality of herbal products varies with the time under the influence of environmental factors, especially temperature, humidity, and oxygen and enables recommended storage conditions, retest periods and shelf lives to be established. In order to do this, it is necessary to monitor compliance of the herbal products with a suitable quality specification throughout the shelf life.
Since last one decade India has seen tremendous growth in herbal drug market, which has resulted in development of numerous proprietary herbal drug formulations by various manufacturers, majority of them comprising of polyherbal formulations. With the advancement of knowledge in the field of phytochemistry it has now been observed that many of these constituents present in the drug may react with each other raising the serious concern about the stability of such formulations. This is the area, which needs to be addressed in order to determine the efficacy of the formulation. This article is aimed to give some guidelines for undertaking stability studies for herbal products.
Stability testing of herbal products is a challenging task, because the entire herb or herbal product is regarded as the active substance, regardless of whether constituents with defined therapeutic activity are known. The objective of a stability testing is to provide evidence on how the quality of the herbal products varies with the time under the influence of environmental factors such as temperature, light, oxygen, moisture, other ingredient or excipient in the dosage form, particle size of drug, microbial contamination, trace metal contamination, leaching from the container, etc. and to establish a recommended storage condition, retest period and shelf-life. Therefore evaluation of the parameters based upon chemical, physical, microbiological, therapeutic and toxicological studies can serve as an important tool in stability studies.