Investigating the critical formulation temperatures of Brucella abortus S-19 vaccine with different liyoprotectants prior to liyophilisation

The aim of this study is to determine the critical temperatures of formulations composed of B.abortus S19 vaccine strain and liyoprotectants. It also attempts to obtain the necessary information that may be beneficial for the optimisation of lyophilisation process by the help of comparative results among formulations. Thermal analysis of 9 different formulations consisting of S19 strain and each of 3 lyprotectants (mannitol, sucrose, trehalose) at 3 different concentrations (5%, 10%,15%) was carried out by freze drying microscopy (FDM), differential thermal analysis (DTA), and electrical impedance (Zsin) analysis. Correlations between liyoprotectant choice and liyoprotectant concentration were investigated by the help of critical formulation temperatures obtained through thermal analysis and screening instruments. Significant differences in the critical temperature of vaccine with liyoprotectant formulation were observed when a different liyoprotectant was used. However, differences that require the redesign of the whole drying process were not observed at the different concentrations of the same liyoprotectant. For this reason, in the quide of a baseline recipe, evaluation of the liyophilisation process carried out through increasing the amount of liyoprotectant can be recommended to increase stability and performance