Within a study of optimization of auxiliary substances in the formulation of a hydrogel containing a potential local anaesthetic agent, substance XXII B, the paper evaluated the effect of a preservative (Ajatin) and humectants (glycerol, propylene glycol, sorbitol) on selected physicochemical indices, which included the partition coefficient, surface tension, and viscosity of the solutions of potential drug XXII B. On the basis of the statistical evaluation of the results, the optimal combination of auxiliary substances in this case seems to be Ajatin + glycerol.

        Key words: potential drugs XXII B – humectants – preservatives – physiochemical indices