The effect of spironolactone on genital skin 5α-reductase activity

The effect of spironolactone (S) on genital skin 5α-reductase activity (5α-RA) of hirsute women (HW) in vivo as well as in normal genital skin in vitro was evaluated. Thirteen HW (Ferriman-Gallwey score of 23.3 ± 2.8) received S 100mg twice a day for a month. Twenty-three non-hirsute women were selected as controls for the assessment of genital skin 5α-RA. S was added to incubations of genital skin from 9 additional controls in vitro in concentrations from 1.2 × 10 −8 to 10 −5 M. HW had significantly higher conversion ratios (CR) of T to DHT compared to controls ( P < 0.05). Post treatment values for the CR T to DHT were significantly lower than prior to S (17.5 ± 1.7 and 8.05 ± 1.2%, P < 0.05) and the mass of DHT produced also decreased by 37 ± 9% ( P < 0.05). The CR T to 3α-diol decreased by 30 ± 9% ( P < 0.05). In 11 of 13 women, a significant reduction of 5α-RA was demonstrated while in 2 patients the activity remained unchanged. The maximum in vitro inhibitory effect of S on the CR T to DHT occurred with a concentration of 1.2 × 10 −5 M ( P < 0.01). In conclusion, S has a direct inhibitory effect on 5α-RA. The beneficial effect of S treatment in HW may be related, in part, to this inhibition of 5α-RA.