Finasteride-d₉is intended for use as an internal standard for the quantification of finasteride by GC- or LC-MS. Finasteride is a 4-azasteroid competitive inhibitor of 5α-reductase type II (IC₅₀= 4.2 nM) and a derivative of testosterone.¹It is 100-fold selective for 5α-reductase type II over type I. Finasteride (10 µM) does not affect the growth of androgen-refractory PC3 prostate cancer cells but increases the protein levels of Nrf2 and heme oxygenase-1 (HO-1).²It decreases prostatic diameter and volume, as well as dihydrotestosterone, but not testosterone, serum levels in dogs with spontaneous benign prostatic hypertrophy when administered at doses of 0.1 and 0.5 mg/kg.³Finasteride reduces testosterone-induced type I procollagen and TGF-β1 protein levels in cultured human scalp dermal fibroblasts in a model of androgenic alopecia when applied at a concentration of 0.1 μM.⁴Formulations containing finasteride have been used in the treatment of benign prostatic hyperplasia and androgenic alopecia in men.

1.Flores, E., Bratoeff, E., Cabeza, M., et al.Steroid 5α-reductase inhibitorsMini Rev. Med. Chem.3(3)225-237(2003) 2.Yun, D.-K., Lee, J., and Keum, Y.-S.Finasteride increases the expression of hemoxygenase-1 (HO-1) and NF-E2-related factor-2 (Nrf2) proteins in PC-3 cells: Implication of finasteride-mediated high-grade prostate tumor occurenceBiomol. Ther. (Seoul)21(1)49-53(2013) 3.Sirinarumitr, K., Johnston, S.D., Kustritz, M.V.R., et al.Effects of finasteride on size of the prostate gland and semen quality in dogs with benign prostatic hypertrophyJ. Am. Vet. Med. Assoc.218(8)1275-1280(2001) 4.Yoo, H.G., Kim, J.S., Lee, S.R., et al.Perifollicular fibrosis: Pathogenetic role in androgenetic alopeciaBiol. Pharm. Bull.29(6)1246-1250(2006)