Effects of Mixing Procedure Itself on the Structure, Viscosity, and Spreadability of White Petrolatum and Salicylic Acid Ointment and the Skin Permeation of Salicylic Acid

White petrolatum is a mixture of solid and liquid hydrocarbons and its structure can be affected by shear stress. Thus, it might also induce changes in its rheological properties. In this study, we used polarization microscopy to investigate how different mixing methods affect the structure of white petrolatum. We used two different mixing methods, mixing using a rotation/revolution mixer and mixing using an ointment slab and an ointment...