Finasteride-loaded poly(lactic-co-glycolic acid) nanoparticles enhance efficacy in hair regrowth: Preparation, characterization, and in vivo study

Alopecia is a multifactorial condition characterized by progressive hair loss that significantly impacts quality of life. Finasteride, a type II 5α-reductase inhibitor, is widely used in the treatment of androgenetic alopecia by blocking the conversion of testosterone to dihydrotestosterone (DHT); however, its long-term oral administration is associated with undesirable systemic adverse effects. In this context, polymeric nanoparticles have emerged as a promising strategy to improve drug delivery efficiency and safety. This study aimed to develop and characterize finasteride-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles and to evaluate their in vivo efficacy following oral administration for promoting hair regrowth. Nanoparticles were prepared by nanoprecipitation and characterized by dynamic light scattering, zeta potential analysis, scanning electron microscopy, and encapsulation efficiency. In vivo evaluation included hair thickness measurement, histological analysis of hair follicle morphology, quantification of finasteride in rat skin, and assessment of renal and hepatic biochemical markers. The nanoparticles exhibited a mean diameter below 200 nm, negative surface charge (approximately −20 mV), spherical morphology, and high encapsulation efficiency (>90%). Oral administration of finasteride-loaded nanoparticles significantly enhanced hair growth, as evidenced by increased hair bulb diameter (∼100 μm), reduced bulb-to-subcutaneous tissue distance (∼884 μm), and increased hair follicle length (∼200 μm). Higher finasteride levels were detected in the skin of animals treated with the nanoparticle formulation compared with free finasteride, without inducing hepatic or renal toxicity. Overall, these findings demonstrate that orally administered finasteride-loaded PLGA nanoparticles enhance hair regrowth and follicular parameters in vivo , supporting their potential as a safer therapeutic strategy for androgenetic alopecia.