Abiraterone 250 mg (Zytiga) is a non-steroidal drug with an antitumor antiandrogenic effect, used in the combined treatment of metastatic castration-resistant prostate cancer. tablets: oval biconvex, from white to almost white, engraved "AA250" (in a cardboard box 1 bottle of 120 tablets); film-coated tablets: oval biconvex, brownish-pink, on one side with an engraving "AA", on the other side - "500" (in a cardboard box 5 blisters of 6 or 12 tablets). Abiraterone 250 mg (Zytiga) acetate - the active substance of Zytigi, is transformed into Abiraterone 250 mg (Zytiga), which is an inhibitor of androgen synthesis. Abiraterone 250 mg (Zytiga), in particular, selectively inhibits the activity of the enzyme CYP17 (17a-hydroxylase / C17,20-lyase), which is expressed and is required for androgen biosynthesis in the adrenal glands, testes and prostate tumor cells. CYP17 catalyzes the transformation of progesterone and pregnenolone by 17a-hydroxylation and cleavage of the C 17.20 bond to dehydroepiandrosterone and androstenedione (respectively), which are testosterone precursors. Also, against the background of inhibition of CYP17 activity in the adrenal glands, the biosynthesis of mineralocorticoids is enhanced. Androgen-sensitive prostate cancer responds to androgen-lowering therapy. Thanks to antiandrogenic therapy (for example, orchiectomy or the use of gonadotropin-releasing hormone agonists - luliberin), androgen biosynthesis is weakened in the testes. However, it does not affect the synthesis of androgens in the adrenal glands and in the tumor.