Development of Delivery Systems for Passive and Iontophoretic Topical Administration of Minoxidil in the Treatment of Androgenic Alopecia

The study investigated the in vitro skin permeation of minoxidil sulfate (MXS) for treating androgenic alopecia, using both micro-encapsulated and non-encapsulated forms, with and without iontophoresis. It was found that anodal iontophoresis increased the passive drug flux through the skin by 150 times, and adjusting the formulation's pH from 3.5 to 5.5 restricted iontophoretic permeation by 3 times while increasing retention in the stratum corneum and hair follicles. Chitosan microparticles containing MXS were developed, showing high encapsulation efficiency (~82%) and sustained drug release 3.5 times longer. These microparticles reduced passive drug permeation by 2 times and increased follicular retention by 5 times. Iontophoresis further enhanced follicular drug retention by 6 times within 3 hours, ensuring rapid delivery to the target site. This system potentially reduced the frequency of application needed by patients.