Reversible Decreases of Fertility in Male Sprague-Dawley Rats Treated Orally with Finasteride, a 5α-Reductase Inhibitor

The study investigated the effects of finasteride, a 5α-reductase inhibitor, on the fertility of male Sprague-Dawley rats. The results showed that the drug caused reversible decreases in fertility, with significant decreases in fecundity and fertility indexes observed in rats administered 80 mg/kg/day. However, there was no apparent effect on the libido of the rats. The study also found that the drug did not adversely affect preimplantation loss, the number of implants or live fetuses per litter, the resorption rate, or the average fetal weight. After a 6-week recovery period, the fertility and fecundity indexes returned to control levels.