AKR1D1 inhibition by finasteride and dutasteride using cortisone (a), cortisol (b) and corticosterone (c) as substrates in a cell free system using recombinant human protein, as measured by NADPH reduction for 35 min. Data are expressed as % enzyme activity of n = 3 replicates. Effect of finasteride and dutasteride on AKR1D1 mRNA expression (d). Effect of finasteride and dutasteride on AKR1D1 activity, as measured by cortisone clearance (e) and 5β-THE generation (f), in HepG2 cells. qPCR data were normalised to 18SrRNA. Data are expressed as mean ± se of n = 3 experiments (*p < 0.05, **p < 0.01, ***p < 0.001, compared to control).