Statistical procedures for optimizing the freeze-drying of a model drug in ter-butyl alcohol:water mixtures

Ter-butyl alcohol:water mixtures were assessed as solvents for gentamicin freeze-drying: the alcohol:water mixtures shortened the total duration of the process, but a bulking agent, such as maltose, was required. While maltose facilitated the reconstruction of the dried product, it also increased the lyophilization time. The composition of the solution to be freeze-dried was optimized in order to reduce the duration of the process, while maintaining a good quality of the lyophilisate. This optimization was carried out using the Experimental Design technique and the Multi-Criteria Decision Making (MCDM) method, and the time needed for freeze-drying was reduced from 39 to about 28 h, while the porous structure of the product was maintained.