Androgenetic alopecia is the most common non-scarring hair loss in men. In genetically predisposed individuals, androgens affect hair follicles by transforming terminal hair into vellus-like miniaturized hair. This process leads to gradual hair loss.
In addition, Tthe enzyme 5α-reductase (5AR) mediates the conversion of testosterone to dihydrotestosterone (DHT). The 5AR family consists of three types: I, II, and III. These enzymes play a role in the metabolism of bile, androgens, and estrogens. Besides, type II 5AR is abundantly expressed in the prostate and hair follicles. Furthermore, men with pattern baldness often exhibit elevated type II 5AR activity along with increased DHT levels in the scalp. These findings support the significant roles of the type II isoenzyme and DHT in androgenetic alopecia. Therefore, Finasteride (MK-906), an orally active and competitive inhibitor of 5α-reductase, is very potential. Afterwards, it has an IC50 of 4.2 nM for type II 5AR and is valuable in studies related to benign prostatic hyperplasia (BPH) and androgenetic alopecia (AGA).
Finasteride is an orally active 5α-reductase inhibitor with anti-myelofibrosis activity.
In vitro, Finasteride inhibits the type II 5α-reductase isoenzyme with 100-fold greater selectivity than the type I isoenzyme. Additionally, at a concentration of 25 µM, Finasteride reduces prostate-specific antigen (PSA) secretion and expression in LNCaP cells. It works by inhibiting the formation of complexes between the androgen receptor and steroid receptor-binding consensus in the promoter region of the PSA gene.
In vivo, Finasteride (0.1-0.5 mg/kg; p.o. once daily for 16 weeks) reduces prostatic size in dogs with BPH without adversely affecting semen quality or serum testosterone concentration. Moreover, Finasteride decreases prostatic diameter (20%), prostatic volume (43%), and serum DHT concentration (58%).
In summary, Finasteride is a potent 5α-reductase inhibitor, and is potential for research of hair loss, benign prostatic hyperplasia, and androgenetic alopecia (AGA).
References:
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