EFFECTS OF A NEW NONSTEROIDAL 5-ALPHA-REDUCTASE INHIBITOR, FK143, ON THE PROSTATE-GLAND IN BEAGLE DOGS

phenyl)methylamino]benzoyl]-1H-indol-1-yl]-butyric acid) is a new non- steroidal inhibitor of steroid 5 alpha-reductase (5 alpha-reductase). The effects of FK143 on prostate size and histopathology of mature mal e beagle dogs were investigated and compared with those of finasteride (a steroidal 5 alpha-reductase inhibitor), and allylestrenol and chlo rmadinone acetate (CMA) (androgen receptor antagonists). FK143 was ora lly administered to the dogs daily for 12 weeks. At doses of 10 and 32 mg/kg, FK143 significantly reduced prostate volume to about 60% of th e initial value, and dogs treated with FK143 showed a dose-dependent g landular epithelial atrophy in the prostate. FK143 showed no abnormal changes in organ weights and histopathology of the adrenal, testis, pi tuitary and liver. The degree of prostate reduction in the dogs treate d with FK143 (10 and 32 mg/kg) was almost the same as that by finaster ide (1.0 mg/kg) and smaller than that by allylestrenol (10 mg/kg) or C MA (10 mg/kg). However, allylestrenol increased liver weights, and CMA increased liver and reduced adrenal weights. These results demonstrat e that FK143 can decrease the volume of the dog prostate without any i nfluence on other organs, and they suggest that FK143 is a good candid ate for the treatment for benign prostatic hyperplasia.