Animal experiment:

Rats: Adult male rats weighing 160-180 g at the start of the study are treated orally once daily for 14 consecutive days either with increasing doses of CGP-53153 (1, 3 and 10 mg/kg) or with 10 mg/kg finasteride in 20% HCD. Control rats are given 20% HCD. On the 14th treatment day, 4 h after the last application, the animals are randomized and rapidly killed. Trunk blood is collected in polystyrene tubes and serum obtained by centrifugation is stored at -20℃ for hormone (T, DHT and rat-LH) determination at a later date. After decapitation, the following organs are excised and weighed after removal of adhering fat and connective tissue: ventral prostate, seminal vesicles, levator ani and bulbocavernosus muscle, testes, pituitary, adrenals, thyroid, thymus and liver[1].

CGP-53153 is a steroidal inhibitor of 5 alpha reductase with IC50s of 36 and 262 nM in rat and human prostatic tissue, respectively.

CGP-53153 competitively inhibits rat microsomal 5 alpha reductase from prostate with an IC50 of 36 nM compared to the reference compound finasteride (IC50=11 nM). CGP 53153 is approximately one order of magnitude more potent in inhibiting rat compared to human 5 alpha reductase, with IC50 values of 36 and 262 nM, respectively

CGP-53153 can significantly reduce T-propionate-mediated prostate growth at oral doses of 0.01 mg/kg. CGP-53153 significantly reduces prostate weight at 3 and 10 mg/kg by 31% and 37%, respectively. Treatment for 12 weeks with both CGP-53153 reduces prostate volume by more than 70% in individual dogs. Neither body weight nor the weight of any organ tested is affected by CGP-53153[1].

[1]. H?usler A, et al. CGP-53153: a new potent inhibitor of 5alpha-reductase. J Steroid Biochem Mol Biol. 1996 Feb;57(3-4):187-95.