2023 AIChE Annual Meeting
Temperature Dependence of Viscosity for Mineral Oils Used in Drug Patches
One application of mineral oil-based gels is for use as transdermal drug patches that diffuse a drug into a patient through their skin. The rate of the drug diffusion out of the patch is vital to effectiveness and safety of drug patches. Mineral oils of varying viscosities can be used in these drug patches and the viscosity of the oil used in the gel influences the diffusion rate of the drug out of the patch. Additionally, the temperature of the gels could vary depending on which part of the body the patch is applied to and the climate that the patient is living in. Intuitively, it makes sense that higher temperatures and lower viscosity oils will result in gels with higher diffusion rates, but quantifying the relationship between the temperature, viscosity, and diffusion rates of the drug through patches is important for designing the desired release from drug patches. As a first step toward this overarching goal, we examine and compare the temperature-dependent viscosity of several aliphatic mineral oils (squalane, Hydrobrite® 200, 380, 550, and 1000). We observe lower viscosities at higher temperatures, as would be expected, but the strength of this correlation depends on the specific mineral oil. The correlation strength between viscosity and temperature is quantified by the Arrhenius Equation, specifically the activation energy associated with flow of the mineral oils. Ultimately, an Arrhenius Equation model can be made to predict viscosity of an oil at different temperatures which can then be used to predict drug diffusion rate for patches made with different oils.