Interaction of beta 2-adrenoceptor agonists with native cyclodextrins: application to the development of chiral...

The enantioselectivity of the complexation between beta 2-adrenoceptor agonists of different structural types and native cyclodextrins (alpha, beta and gamma-CDs) has been examined by including CDs as chiral modifiers in high pressure liquid chromatography (HPLC) and in capillary zone electrophoresis (CZE). The best enantiomer separation was obtained for terbutaline with beta-CD in both HPLC and CZE systems (resolution (Rs) of 1.0 and 1.1 respectively). The chiral HPLC assay for terbutaline was validated and gave linear standard curves of peak height versus concentration for both enantiomers (r2 > 0.99) with y-intercepts through the origin and intra- and interday coefficients of variation of less than 3% at 100 micrograms ml-1. Only the enantiomers of the resorcinol type beta 2-agonists terbutaline and orciprenaline were separated in the CZE and HPLC systems, suggesting the position of substituents in the aromatic ring of beta 2-agonists has a profound effect on the enantioselectivity of complexation of these drugs with beta-CD.