Abstract
In order to examine the physicochemical stability of drugs, utilizing solubilization with nonionic surface active agents, a model experiment was carried out. Tween 80 was selected as the nonionic surfactant, used in a 10% aqueous solution, and caproic acid was used as the solubilizate. Test solutions were prepared with caproic acid solubilized with various amounts of 10% Tween 80 solution, and its physicochemical properties, such as surface tension, relative viscosity, density, lowering of freezing point, and pH, were continuously measured, in order to examine the effect of the micelle so formed by temperature changes and changes in the dispersion in the solution after preservation for a long period. Surfactant solution, especially with a solubilizate, shows sensitive and marked changes by warming or heating but when the solubilizate is a stable substance like caproic acid, the solution returns to the original state and the physicochemical properties also return to the normal, if the conditions are removed in short-time loading. In the case of preservations over a long period of time, the test solutions were found to undergo change which was incapable of returning to the original state.
