The Effect of Various Vehicles on the In Vitro Skin Permeability of Minoxidil

Background: This study aimed to examine the uptake of the model therapeutic agent, minoxidil, through the skin, under the influence of different vehicles. Therefore, the effect of different penetration enhancers such as Propylene glycol, water, ethanol, transcutol P, caprylic acid, and Isopropyl alcohol were evaluated on skin permeability of minoxidil through rat skin. Methods: The skin permeability of minoxidil on rat skin was analyzed through a Franz cell by evaluating the parameters, including J ss, ERflux, ERD, and ERp. The enhancement mechanisms were studied by comparing FT-IR peak intensities for asymmetric and symmetric C-H stretching, ester C=O stretching, and Amide peaks. The mean transition temperature (Tm) and their enthalpies (ΔH) were investigated by the DSC technique. Results: Caprylic acid had the highest diffusion coefficient enhancement ratio (ERD), followed by propylene glycol and water. All solvents have ERD flux enhancement ratio. Solubility in the stratum corneum limited partitioning. All carriers enhanced drug permeability from rat skin, according to FTIR and DSC. Conclusions: Caprylic acid is an effective topical vehicle for minoxidil due to greater partitioning and diffusion through rat skin.