Highly sensitive and specific time-resolved fluoroimmunoassay (TR-FIA) of cyproterone acetate and free cyproterone

We have developed a non-isotopic TR-FIA for Cyproterone acetate and Cyproterone in plasma. Synthesis of the biotinylated tracers, biotinylated Cyproterone acetate, and Cyproterone, as well as the preparation of anti–Cyproterone acetate and anti-Cyproterone antisera are reported. The specificity of anti-Cyproterone acetate antiserum resulting from the coupling of link bridge (link bridge between steroid and BSA), on the 3-position on the steroid skeleton, allowed to carry out the Cyproterone acetate assay directly on extracted plasma (without chromatography). On the other hand Cyproterone assays require a purification step, including extraction plus chromatography, because the plasma Cyproterone acetate concentrations in Cyproterone acetate-treated women are 200 times higher than for Cyproterone. Theses plasma TR-FIA of Cyproterone acetate and Cyproterone presented the advantage of needing only small doses of radioactivity for recovery controls, and better praticability related to the only existing RIA described to date.