Chitosan nanoparticles for targeting and sustaining minoxidil sulphate delivery to hair follicles

This work developed minoxidil sulphate-loaded chitosan nanoparticles (MXS-NP) for targeted delivery to hair follicles, which could sustain drug release and improve the topical treatment of alopecia. Chitosan nanoparticles were obtained using low-molecular weight chitosan and tripolyphosphate as crosslink agent. MXS-NP presented a monomodal distribution with hydrodynamic diameter of 235.5 ± 99.9 nm (PDI of 0.31 ± 0.01) and positive zeta potential (+38.6 ± 6.0 mV). SEM analysis confirmed nanoparticles average size and spherical shape. A drug loading efficiency of 73.0 ± 0.3% was obtained with polymer:drug ratio of 1:1 (w/w). Drug release through cellulose acetate membranes from MXS-NP was sustained in about 5 times in comparison to the diffusion rate of MXS from the solution (188.9 ± 6.0 μg/cm2/h and 35.4 ± 1.8 μg/cm2/h). Drug permeation studies through the skin in vitro, followed by selective recovery of MXS from the hair follicles, showed that MXS-NP application resulted in a two-fold MXS increase into hair follicles after 6 h in comparison to the control solution (5.9 ± 0.6 μg/cm2 and 2.9 ± 0.8 μg/cm2). MXS-loading in nanoparticles appears as a promising and easy strategy to target and sustain drug delivery to hair follicles, which may improve the topical treatment of alopecia.