External genitalia abnormalities in male rats exposed in utero to finasteride, a 5α-reductase inhibitor

July 1990 in “Teratology”

R. M. Clark, Joseph M. Antonello, S. J. Grossman, Lawrence D. Wise, Craig S. Anderson, Walter Bagdon, S. Prahalada, J. A. Macdonald, R. G. H. Robertson

TLDR Finasteride exposure in pregnancy causes genital abnormalities in male rats.

The study investigated the effects of in utero exposure to finasteride, a 5α-reductase inhibitor, on male rats. The results showed that exposure to finasteride caused external genitalia abnormalities, including hypospadias and decreased anogenital distance. The study suggests that exposure of women of childbearing potential to even low levels of finasteride should be avoided due to the risk of inducing hypospadias in male offspring. The study also highlights the role of DHT in the growth of the perineal region in males.

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Cited in this study

research Nipple Differentiation in Fetal Male Rats Treated with an Inhibitor of the Enzyme 5α-Reductase: Definition of a Selective Role for Dihydrotestosterone*

53 citations , January 1986 in “Endocrinology”

Blocking a specific enzyme in male rat fetuses leads to the development of nipples and feminized genitalia.

research External genitalia abnormalities in male rats exposed in utero to finasteride, a 5α-reductase inhibitor

122 citations , July 1990 in “Teratology”

Finasteride exposure in pregnancy causes genital abnormalities in male rats.