LY191704

LY191704, as a benzoquinolinone, is a potent, nonsteroidal, noncompetitive and selective human type I 5α-reductase inhibitor. LY191704 is a racemic mixture of the compounds LY300502 and LY300503. LY191704 may be useful in the research of human endocrine disorders associated with overproduction of dihydrotestosterone (DHT) by 5α-reductase type 1^[1][2]. IC50 & Target: Human Type I 5α-Reductase^[1][2] In Vitro: LY191704 (0.001-100 uM) inhibits the conversion of testosterone to DHT with an IC₅₀ of 10 nM in Hs68 cells. LY191704 inhibits the enzyme expressed by the human cells with an IC₅₀ of 12 nM but is virtually inactive against the 5α-reductase expressed by rat prostate cells. LY191704 is a potent and specific inhibitor of human 5α-reductase type 1 but had little or no activity against human 5α-reductase type 2 or rat 5α-reductase type 1. A K_i value of 17.1 μM is determined for the human type 2 enzyme, indicating that LY191704 demonstrates an 5000-fold selectivity for the human type 1 isozyme^[2]. In Vivo: LY191704 (10, 30, or 100 mg/kg; p.o.; 1 month) increases plasma concentrations^[1].