indication

For the palliative treatment of patients with advanced prostatic carcinoma.

pharmacology

Cyproterone is an antiandrogen. It suppresses the actions of testosterone (and its metabolite dihydrotestosterone) on tissues. It acts by blocking androgen receptors which prevents androgens from binding to them and suppresses luteinizing hormone (which in turn reduces testosterone levels).

mechanism of action

The direct antiandrogenic effect of cyproterone is blockage of the binding of dihydrotestosterone to the specific receptors in the prostatic carcinoma cell. In addition, cyproterone exerts a negative feed-back on the hypothalamo-pituitary axis, by inhibiting the secretion of luteinizing hormone resulting in diminished production of testicular testosterone.

biotransformation

Primarily hepatic. Cyproterone acetate is metabolized by the CYP3A4 enzyme, forming the active metabolite 15beta-hydroxycyproterone acetate, which retains its antiandrogen activity, but has reduced progestational activity.

absorption

Completely absorbed following oral administration.

half life

Elimination Following oral or intramuscular administration, the plasma half-life is 38 and 96 hours, respectively.

route of elimination

It is excreted approximately 60% in the bile and 33% through the kidneys.