STUDY ON THE RULE OF DISCOLORATION AND PREDICTION OF SHELF-LIFE OF STREPTOMYCIN SULFATE INJECTION

The present paper explores the rule of discoloration of streptomycin sulfate injection (500,000 u/2 ml) of two formulations with different stability agent at various temperatures. Experimental data indicate that the rule of discoloration of the injection may be represented by the following regression equation: (A-A₀) = a + bt^1、5 where A₀ is the initial absorbance of the injection, A is the absorbance at time t, a, b are the regression coefficients. The rate equation of discoloration of the streptomycin sulfate injection is dA/dt = k(A-A₀-a^1/3 where k is the rate constant of discoloration of the injection. It is seen from the equation that the discoloration of the injection is not a simple order reaction.According to the rule of discoloration of streptomycin sulfate injection and Arrhenius exponent equation, the accelerated analysis for stabilization of the injection was made by classical isothermal mehtod and initial mean velocity method. Shelf-life of the injection was calculated by classical isothermal method, initial mean velocity method and the Weibull probability paper method. Shelf-life was about 20 months, and also fundamentally coincident with the value obtained from the samples reserved for observation at room temperature. The activation energy of discoloration reaction of the injection obtained from the above three methodsappeared to be the same.