Effect of Finasteride on Adrenal Steroidogenesis in Men

In a study conducted 29 years ago, 10 healthy men were given 5 mg of finasteride daily for 28 days to determine its effect on adrenal steroidogenesis. The results showed that finasteride significantly decreased serum dihydrotestosterone levels from 31 +/- 5 to 4.4 +/- 1.2 ng/dl. However, there were no significant changes in basal or ACTH-stimulated serum levels of adrenal steroids. There was also no significant decrease in the product to precursor ratio for the seven adrenal enzymes tested. Finasteride increased mean serum androstenedione levels by 17% and significantly increased the androstenedione to 17-hydroxyprogesterone ratio. The study concluded that finasteride has no detectable effect on adrenal steroidogenesis, other than that which can be explained by inhibition of the 5 alpha-reductase enzyme.