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. 
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 [alpha 1-acid glycoprotein (AGP) and human serum albumin (HSA)].  The binding parameters characterizing the high-affinity binding site of AGP evaluated by using capillary electrophoresis [Ka(RS) = (3.01 +/- 1.15).10(6) l/mol; Ka(S) = (2.13 +/- 0.53).10(6) l/mol; Ka(R) = (4.88 +/- 1.57).10(6) l/mol] were in good accordance with those obtained by HPLC [Ka(RS) = (3.88 +/- 1.74).10(6) l/mol: Ka(S) = (1.80 +/- 0.53) x 10(6) l/mol; Ka(R) = (5.43 +/- 2.53).10(6) l/mol].  Relatively small quantitative differences have been observed considering the attachment of (R)-carvedilol to the secondary low-affinity binding sites on alpha 1-acid glycoprotein by comparing these two methods.  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.