A reversed-phase high-performance liquid chromatographic method for the simultaneous determination of cyproterone acetate (CPA), 15β-hydroxycyproterone acetate (15β-OH-CPA) and cyproterone (CP) was reported. This method was specific, sensitive, precise, easy and rapid for determination of the serum concentrations of these steroids in patients receiving CPA. Although no peak corresponding to CP was observed for serum, peaks corresponding to CPA and 15β-OH-CPA were detected and well separated in all subjects undergoing long-term CPA therapy. In these patients, there seemed to be a dose-dependent relationship between the amount of CPA administered and the serum concentrations of these steroids, and the serum concentrations of CPA were either similar or low compared with those of 15β-OH-CPA.
In conclusion, this simplified method is thought to be very valuable for studies on the pharmacokinetics of CPA and 15β-OH-CPA, and on the relationship between the CPA dosage and the therapeutic or side effects on adrenal and gonadal steroid production.