15β-Hydroxycyproterone acetate

15β-Hydroxycyproterone acetate is a steroidal antiandrogen and the major metabolite of cyproterone acetate. It is formed from CPA in the liver by hydroxylation via the cytochrome P450 enzyme CYP3A4. During therapy with CPA, 15β-OH-CPA circulates at concentrations that are approximately twice those of CPA. 15β-OH-CPA has similar or even greater antiandrogen activity compared to CPA. However, it has only about one-tenth of the activity of CPA as a progestogen. 15β-OH-CPA also shows some glucocorticoid activity, similarly to CPA and unesterified cyproterone.