Transdermal delivery of mixnoxidil with block copolymer nanoparticles

The study evaluated the effect of nanoparticle size on the skin penetration of minoxidil using 40- and 130-nm self-assembled nanoparticles in both hairy and hairless guinea pigs. Results showed that in hairy guinea pig skin, 40-nm nanoparticles had 1.5-fold higher permeation in the epidermal layer and 1.7-fold higher in the receptor solution compared to 130-nm nanoparticles. No size-dependent permeation differences were observed in hairless guinea pig skin. Phospholipid liposomes and ethanol–water admixture did not show permeation differences regardless of hair follicles. Confocal microscopy and permeation results indicated that nanoparticles penetrated mainly via hair follicles, enhancing skin absorption of solutes.