The use of finasteride for alleviating hair loss has been investigated, and it has been
applied as an oral dose medication. However, due to the inconvenience of daily drug
administration over long period of time, novel controllable finasteride delivery has been
actively investigated. As a novel method of finasteride delivery, the development of
finasteride-loaded microspheres for subcutaneous administration is becoming increasingly
pharmaceutically important. Therefore, the present study aimed to use finasteride-loaded
microspheres in a controlled manner in an attempt to overcome the limitations of the oral
administration of finasteride and to cause fewer adverse effects. Finasteride-loaded
microspheres containing poly(lactic-co-glycolic acid) and finasteride at a ratio of 4:1
were prepared, and a testosterone-induced androgenic alopecia mouse model was used.
Following observation for 10 weeks, the percentage hair growth was 86.7% (total hair
growth 60%, partial hair growth 26.7%) in the orally-applied finasteride-treated group as
a positive control, and 93.3% (total hair growth 60%, partial hair growth 33.3%) in the
finasteride-loaded microspheres-treated group. Serum dihydrotestosterone levels began to
decrease at week 6 in the orally-applied finasteride- and finasteride-loaded
microsphere-treated groups. In addition, the finasteride-loaded microspheres-treated group
exhibited similar follicular number, follicular length, anagen/telogen ratio and hair bulb
diameter values to those of the orally-applied finasteride-treated group. Furthermore, the
finasteride-loaded microspheres increased the activities of phosphoinositide
3-kinase/protein kinase B and Wnt/β-catenin in relation to hair follicle cell
growth signaling in mouse skin, and suppressed the apoptosis of hair follicle cells by
reducing the expression of transforming growth factor-β2 and caspase-3, which are
indicators of apoptosis. In conclusion, the administration of a single injection of
finasteride-loaded microspheres was effective in treating testosterone-induced alopecia.
Furthermore, it led to equivalent hair growth effects when compared with orally-applied
finasteride, thus revealing the possibility of effective treatment via different routes of
administration.