Thermodynamic stability of solid pharmaceutical formulations

This paper deals with the application of rigorous stability analysis and pr edict time for degradation of solid pharmaceutical formulations. The stabil ity analysis in the form of the tangent-plane criterion is used to predict the stability of certain solid formulations. The Michelsen vector which ind icates instability when the sum of its components is greater than unity is differentiated with respect to time and the results are used to predict whe n instability sets in. The total degradation time is the sum of the time fo r instability to set in and the time for the mole fraction to reach a certa in value.