CZE analysis of the antibiotic vancomycin in commercial formulations and in innovative microparticles

Vancomycin is a glicopeptide antibiotic, isolated from the soil microorganism Streptomyces orientalis, which is used for the treatment of severe infections caused by Gram-positive organisms; Vancomycin is administred in parenteral form for the treatment of endocarditis and other severe infections and in oral form for the treatment of colon infections. New formulations are in progress to obtain a controlled release of the drug in the colon site, in order to use the antibiotic for the treatment of specific intestinal patologies. The aim of this work is the development of a quick analytical method for the quality control of commercial oral capsules, vials for intravenous injections and innovative microparticles. The method is based on capillary zone electrophoresis. A 3D-CE Agilent instrument equipped with a diode-array detector was used; fused silica capillaries, with a total capillary length of 48.5 cm and an effective length of 8.5 cm (100 µm internal diameter) were used. The BGE consisted of a 12.5 mM phosphate buffer, whose pH was adjusted to 2.5 using sodium hydroxide. The applied voltage was –20 kV, the detection wavelenght 210 nm, with the capillary thermostatted at 25°C. The samples were diluted in water and injected by pressure (30 mbar for 3 s) from the anodic side of the capillary. An electrophoretic run is completed within 3.0 minutes, using Triprolidine as the internal standard. Good linearity was found in the Vancomycin concentration range from 500 ng/mL to 5 µg/mL with satisfactory precision. After validation, the method was applied to the analysis of commercial capsules, vials and innovative microparticles; preliminary investigations gave satisfactory results.