Analytical and semipreparative high performance liquid chromatography enantioseparation of bicalutamide and its chiral impurities on an immobilized polysaccharide-based chiral stationary phase

• Enantioseparation of bicalutamide and its impurities was studied by HPLC on IA CSP.
• Temperature effects on enantioselectivity and resolution were evaluated.
• A ternary eluent system incorporating ethyl acetate was selected for mg-resolutions.
• In these conditions, 10 mg of the more active (R)-enantiomer of bicalutamide within 15 min were isolated.

Direct HPLC separation of enantiomers of Bicalutamide (BCT), a non-steroidal antiandrogen used for the treatment of prostate cancer, was performed by using the immobilized amylose-based Chiralpak IA chiral stationary phase (CSP). Enantioselective conditions were achieved using standard normal phase mixtures n-hexane-alcohol (ethanol or 2-propanol) and a “non-standard” mobile phase containing ethyl acetate (EA). The chromatographic behaviour of the IA CSP under these elution modes was evaluated and compared at different temperatures. The eluent mixture n-hexane-EA-ethanol 100-30-5 (v/v/v) and the column temperature of 40 °C were identified as the best operational conditions to carry out semipreparative enantioseparations on a 1-cm I.D. IA column. Using this protocol, about 960 mg of (R)-BCT, which is the enantiomer with the almost entire anti-androgenic activity of BCT, per day could be isolated.The analytical and semipreparative HPLC resolution of chiral impurities of BCT, and their empiric absolute configuration assignment by circular dichroism correlation method are also presented.