Comparison of the Hummel—Dreyer method in high-performance liquid chromatography and capillary electrophoresis conditions for study of the interaction of (RS)-, (R)- and (S)-carvedilol with isolated plasma proteins

Abstract The Hummel-Dreyer method in capillary zone electrophoresis was compared with the corresponding high-performance liquid chromatographic (HPLC) variant in order to study the interaction of racemic carvedilol and its individual enantiomers with isolated human plasma proteins [ α 1 -acid glycoprotein (AGP) and human serum albumin (HSA)]. The hinding parameters characterizing the high-affinity binding site of AGP evaluated by using capillary electrophoresis [ K a( RS ) = (3.01±1.15)·10 6 l/mol; K a( S ) =(2.13±0.53)·10 6 l/mol; K a( R ) =(4.88±1.57)·10 6 l/moll were in good accordance with those obtained by HPLC K a( S ) =(3.88+1.74)10 6 l/mol; K a( R ) =(1.80−0.53)×10 6 l/mol; K a( R ) =(5.43±2.53)·10 6 l/moll. Relatively small quantitative differences have been observed considering the attachment of ( R )-carvedilol to the secondary low-affinity binding sites on a,-acid glycoprotein by comparing these two method,. In general, the Hummel-Dreyer method applied to capillary zone electrophoresis conditions was verified to be an efficient and fast technique for reliable description of quantitative binding parameters of hydrophobic drugs.