Enzyme Affinity (Ki) Inhibition type Est. inhibition at 2 μM Cholesterol side-chain cleavage enzyme 20 μM Competitive ? 3β-Hydroxysteroid dehydrogenase/Δ5-4 isomerase 5.8 μM Competitive 4.3% 17α-Hydroxylase 2.4 μM Competitive 2.9% 17,20-Lyase 1.9 μM Competitive 3.9% 17β-Hydroxysteroid dehydrogenase 4.4 μM Competitive 15% 21-Hydroxylase 0.8 μM Competitive 37% 11β-Hydroxylase 1 μM Competitive 21% Aromatase >100 μM – 0%