A Simple and Cost-Effective Synthesis of Sulfated β-Cyclodextrin and Its Application as Chiral Mobile Phase Additive in the Separation of Cloperastine Enantiomers

A new, simple and cost-effective method for the synthesis of sulfated beta-cyclodextrin (S-β-CD), one of the most widely used chiral mobile phase additive, using sulfamic acid as sulfonating agent has been described. The method was optimized and the acquired product was characterized and compared with a marketed Sigma Aldrich sulfated beta-cyclodextrin (S-β-CD1). Beta cyclodextrin (β-CD), hydroxypropyl beta-cyclodextrin (HP-β-CD), S-β-CD1 and S-β-CD2 were evaluated as chiral mobile phase additives (CMPAs) for the enantiomeric separation of cloperastine, an antitussive agent, using reversed-phase HPLC. Under the optimized conditions, a resolution of 3.14 was achieved within 15 minutes on an achiral Kromasil C₈ (150 x 4.6 mm, 5 µ) column with a mobile phase of 5mM monopotassium phosphate containing 10mM S-β-CD3 pH 3 and 45% methanol with a run time of 15 min. The method utilizing S-β-CD3 as CMPA was validated as per ICH guidelines and applied for the quantitative determination of cloperastine enantiomers in active pharmaceutical ingredients and pharmaceutical formulations. The selectivity changes imparted by S-β-CD were proven to be beneficial for chiral separation. The chiral recognition mechanism and elution order of the reported enantiomers were determined by simulation studies. It was observed that inclusion complex formation and hydrogen bonding are the major forces for the chiral resolution.