Solid microneedle booster as an enhanced microneedling platform for the treatment of androgenetic alopecia

Solid microneedle (SMN) is used to enhance transfollicular delivery in androgenetic alopecia (AGA); however, user-dependent kinematics can generate irregular microchannels that require sequential drug application. Here, we developed a one-step solid microneedle booster (SMB) that combines spring-driven perpendicular stamping with simultaneous liquid dosing. This circumvents the spatial and temporal mismatch inherent in traditional two-step methods, improving microchannel reproducibility and early transport. In porcine skin, rhodamine B mapping exhibited higher microchannel surface coverage for SMB than that of the roller at 20 matched applications, with SMB producing deeper penetration. Functional delivery was evaluated by Franz diffusion using ascorbic acid as a hydrophilic probe of microchannel-assisted permeation. Across the various tested conditions, SMB consistently produced a stronger early-phase permeation enhancement than that of the roller, and this early advantage was reflected in the cumulative delivery at later time points. SMB-assisted minoxidil (MXD) delivery accelerated hair regrowth in vivo compared with roller-assisted delivery under matched treatment settings, and histological analysis supported these outcomes as it revealed a greater enrichment of deep follicles in the SMB + MXD groups. Collectively, SMB provides a directionality-controlled, one-step microneedling platform that enhances the early, front-loaded transport and promotes follicular maturation, with AGA serving as a representative model for the broader applications of dermatologic delivery.