Liarozole dihydrochloride (R75251; R85246) is a cytochrome P450 (CYP450) dependent inhibitor, orally bioavailable, it also a potent inhibitor of estrogen (via inhibition of aromatase) and testicular androgen synthesis (inhibition of 17 ,20-lyase). Liarozole dihydrochloride prevents the catabolism of retinoic acid via inhibition of 4-hydroxylase and exhibits retinoid sparing and retinoid-mimetic effects in vivo. Liarozole dihydrochloride is an imidazole analogue; it is being investigated as a non-hormonal agent in prostate cancer and in the treatment of various other cancers and skin disorders.