Microneedle mediated transdermal delivery of β-sitosterol loaded nanostructured lipid nanoparticles for androgenic alopecia

Plant-derived 5 α-reductase inhibitors, such as β-sitosterol and phytosterol glycosides, have been used to treat androgenic alopecia, but their oral absolute bioavailability is poor. This study aimed to develop a transdermal drug delivery system of β-sitosterol (BS) using a nanostructured lipid carrier (NLC) incorporated into polymeric microneedles (MN). Using a high-speed homogenization method, NLC was formulated variables were optimized by Box-Behnken statistical design. The optimized formulation of BS-loaded NLCs was incorporated into the chitosan-based MNs to prepare NLC-loaded polymeric MNs (NLC-MNs) and evaluated using testosterone induced alopecia rats. The cumulative amount of β-sitosterol associated with NLC- MN which penetrated the rat skin in-vitro was 3612.27 ± 120.81 μg/cm², while from the NLC preparation was 2402.35 ± 162.5 μg/cm². The steady state flux (J_ss) of NLC-MN was significantly higher than that of the optimized NLC formulation (P < 0.05). Anagen/telogen ratio was significantly affected by NLC and NLC-MN, which was 2.22 ± 0.34, 1.24 ± 0.18 respectively compared to 0.26 ± 0.08 for animal group treated with testosterone. The reversal of androgen-induced hair loss in animals treated with β-sitosterol was a sign of hair follicle dominance in the anagenic growth phase. However, NLC-MN delivery system has shown significant enhancement of hair growth in rats. From these experimental data, it can be concluded that NLC incorporated MN transdermal system have potential in effective treatment of androgenic alopecia.