Effect of Rubbing Application on the Skin Permeation of Active Ingredients from Lotion and Cream

The study examined how rubbing affects the absorption of caffeine (CAF), a hydrophilic drug, and rhododendrol (RD), a lipophilic drug, from lotions and creams into the skin. It was discovered that rubbing significantly increased the permeation of CAF into the skin for both types of formulations, especially when rubbed against hair growth direction. However, rubbing did not enhance the permeation of RD. The increase in CAF permeation may be due to the enlargement of hair follicle openings caused by rubbing, while RD's lack of enhancement could be attributed to its high distribution in the outer skin layer (stratum corneum). The study, which used porcine skin as a model and had an average sample size of three (n = 3), suggests that rubbing can influence the effectiveness of topical drug delivery, but more research is needed to understand the effects with different drugs and formulations.