Studies on the stability of salvianolic acid B as potential drug material

– Salvianolic acid B (Sal B) is one of the major water‐soluble compounds isolated from the roots of Salvia miltiorrhiza , which is widely used as a traditional Chinese medicine. Although much research on the general stability of Sal B has been undertaken and reported, there is still a need for further study of the stability required as a potential drug material. Objective – To study the stability of Sal B in the solid state and in normal saline (NS) solution during storage, as required in the ICH guidelines (2003) and Chinese Pharmacopoeia (2005). Methodology – Sal B stability was analysed using the high‐performance liquid chromatography (HPLC) method described in the Chinese Pharmacopoeia . HPLC coupled with time‐of‐flight mass spectrometry (HPLC‐TOFMS) was applied for the separation and identification of the degradation products of Sal B. Results – In the solid state, Sal B packaged in aluminium foil bags was stable for 6 months under ‘accelerated conditions’ (40°C, 75% relative humidity, RH). However, solid Sal B degradation was observed under open exposure to stress conditions of high temperature (60°C) or high humidity (92.5 or 75% RH). In NS solution, Sal B underwent severe degradation under accelerated conditions. Through HPLC‐TOFMS, nine degradation products were identified and the possible degradation pathway was deduced. Conclusion – The results demonstrate that the potential drug material Sal B could be used in a solid formulation, but is not suitable for use as a liquid formulation. Copyright © 2011 John Wiley & Sons, Ltd.