The Effect of Vegetable and Volatile Oils on the Piroxicam Skin Permeability: A Mechanistic Study

Background: Piroxicam is a non-steroidal anti-inflammatory medication for treating fever, discomfort, and inflammation. In addition, piroxicam inhibits cyclooxygenase and lowers prostaglandin synthesis, resulting in analgesic and anti-inflammatory effects. Objectives: This study used Franz diffusion cells made from rat skin primed with sesame, eucalyptus, olive, menthol, clove, and sunflower oils. Methods: Control was hydrated rat skin. Permeability measurements include steady-state flux (Jss), permeability coefficient (Kp), and diffusion coefficient (D). FT-IR was used to compare changes in peak position, differential scanning calorimeter (DSC), mean transition temperature, and the permeability enhancement methods of the penetration enhancer (Tm). The skin acted as a barrier to piroxicam permeability throughout the whole surface, indicating that drug flux was limited by diffusion into the skin. Results: The steady-state flux (Jss) of all penetration enhancers were not significantly different from control, except for clove and menthol oil (4 hours treated) and olive oil (2 and 4 hours treated). Conclusions: Penetration enhancers improved drug permeability through rat skin. Sesame oil, menthol oil, and sesame oil were found to have higher ERflux, ERD, and ERP ratios than water-hydrated skin due to lipid fluidization, lipid structure disruption, and irreversible keratin denaturation.