Lack of effect of topical finasteride suggests an endocrine role for dihydrotestosterone  Thomas M Price, M.D., Susan Allen, R.N., G.Vernon Pegram, M.D.  Fertility and Sterility  Volume 74, Issue 2, Pages 414-415 (August 2000) DOI: 10.1016/S0015-0282(00)00600-2

Figure 1 Serum levels of testosterone and dihydrotestosterone were compared by paired t-test at baseline, 3 months, and 6 months of topical finasteride therapy vs. placebo (mean ± SEM). A significant increase in testosterone was seen at 3 months in both the finasteride group (P=.038) and the placebo group (P=.044). There were no differences in testosterone between baseline and 6 months, or between groups. There were no differences in levels of dihydrotestosterone with time or between groups. Dihydrotestosterone: finasteride (□), placebo (■); testosterone: finasteride ( ), placebo ( ). Fertility and Sterility 2000 74, 414-415DOI: (10.1016/S0015-0282(00)00600-2)