Complex sentence: Abiraterone acetate, via its metabolite abiraterone, has the capacity to lower circulating testosterone levels to less than 1 ng/dL (i.e., undetectable), and these concentrations are much lower than those achieved by castration (20 ng/dL).
Split into simpler sentences: Abiraterone acetate, via its metabolite abiraterone, has the capacity to lower circulating testosterone levels to less than 1 ng/dL (i.e., undetectable). These concentrations are much lower than those achieved by castration (20 ng/dL).