Predicting the Expiration Date of Tianning Drop Pill by Multivariate Linear Model and Classical Isothermal Accelerated Tests

OBJECTIVE To study the stability of ferulic acid, the main ingredient of Tianning Drop Pill, and to predict the validity duration. METHODS　The HPLC method was used to determine the content of ferulic acid. Multivariate linear model and classical isothermal kinetic method were used to study the influence of temperature on ferulic acid stability. The efficacy of two methods were verified and compared with long term test. RESULTS It was found that the pyrolytic degradation kinetics of Tianning Drop Pill fitted with the first-order kinetics. The expiration dates of Tianning Drop Pill calculated by multiple linear model and classic isothermal accelerated tests were 21.8 months and 20.8 months, respectively. CONCLUSION The expiration dates of Tianning Drop Pill calculated by two different methods are almost the same. Multivariate linear model can be used for a convenient method to predict the expiration date.