Gestonorone Capronate is a progestin for the treatment of benign prostatic hypertrophy and endometrial cancer. In Vitro: The administration of gestonorone capronate impedes testosterone reduction. The oxydation pathway remains uninfluenced. This inhibition of the formation of 5α-reduction products is present at the lowest dose of gestonorone capronate and is augmented progressively with increasing gestonorone capronate concentration^[1].