In vitro skin permeation of monoolein nanoparticles containing hydroxypropyl β-cyclodextrin/minoxidil complex

Monoolein (MO) cubic phases entrapping hydroxypropyl β-cyclodextrin (HPβCD)/minoxidil (MXD) complex were prepared by hydrating molten MO with the complex solution, where the concentrations of HPβCD/MXD were 1.0%/0.32%–19.4%/1.98%. Without HPβCD, the maximum content of MXD loaded in the cubic phase was only 0.071%, but with aid of HPβCD, the content in the cubic phase increased up to 5.72%. The nanoparticles of the cubic phase were prepared by a bath type sonication using a Pluronic F127 as a dispersant. HPβCD/MXD complex had little effect on the size and the structure of cubic phase nanoparticles. In vitro skin permeation of MXD loaded in the cubic phase nanoparticles (2.44 mg/cm2 for 18 h), were higher than that of MXD dissolved in propylene glycol/water/ethanol (20/30/50, v/v/v) (1.91 mg/cm2 for 18 h), but the amount of MXD remained within skin was higher with the MXD solution (0.068 mg/cm2 for 18 h) than with the nanoparticles (0.023 mg/cm2 for 18 h).