Determination of the binding of a beta 2-blocker drug, frusemide and ceftriaxone to serum proteins by capillary zone electrophoresis.

A modified Hummel-Dreyer method was used to study the binding of drugs with serum proteins by high performance capillary electrophoresis. The study was carried out to check the possible interaction between serum proteins and a highly selective beta 2-blocker, ICI 118551 (ICI). To prove the suitability of the method the protein binding of frusemide and ceftriaxone, drugs previously investigated, was also studied. The analyses were carried out by injecting a solution of s alpha(1)-acidic glycoprotein (alpha(1)-AGP) or human serum albumin in 70 mM NaH2PO4/Na2HPO4(pH 7.4) buffer into an uncoated fused silica capillary filled with the same buffer. In the capillary, maintained at a working temperature of 35 degrees C, a known amount of the ICI, frusemide or ceftriaxone was added. The method allows the bound drug to be determined directly.