Development and validation of automated SPE-LC-MS/MS method for determination of indapamide in human whole blood and its application to real study samples.

A fast and simple liquid chromatography-electrospray ionization tandem mass spectrometry method for determination of indapamide in human whole blood was developed and validated. The sample extraction of indapamide from human whole blood was achieved using automated solid-phase extraction. Chromatographic separation was performed on Kinetex C18 column (100 × 2.1 mm, 1.7 µm particle size) using acetonitrile and 2 mm ammonium formate in ratio 90:10 (v/v) as a mobile phase. The mass spectrometer was operated in the multiple reaction monitoring mode using positive electrospray ionization for indapamide and the internal standard (zolpidem tartarate). The total run time was 2.5 min. The present method was found to be linear in the concentration range of 1-50 ng/mL with the coefficient of determination 0.9987. The absolute recoveries of indapamide were 90.51-93.90%. The method was validated according the recommendations for validation of bioanalytical methods of European Medicines Agency guideline and was successfully used to analyze human whole blood samples for application in a pharmacokinetic study.

Colon-specific delivery of 5-aminosalicylic acid from chitosan-Ca-alginate microparticles.

Chitosan-Ca-alginate microparticles for colon-specific delivery and controlled release of 5-aminosalicylic acid after peroral administration were prepared using spray drying method followed by ionotropic gelation/polyelectrolyte complexation. Physicochemical characterization pointed to the negatively charged particles with spherical morphology having a mean diameter less than 9 microm. Chitosan was localized dominantly in the particle wall, while for alginate, a homogeneous distribution throughout the particles was observed. (1)H NMR, FTIR, X-ray and DSC studies indicated molecularly dispersed drug within the particles with preserved stability during microencapsulation and in simulated in vivo drug release conditions. In vitro drug release studies carried out in simulated in vivo conditions in respect to pH, enzymatic and salt content confirmed the potential of the particles to release the drug in a controlled manner. The diffusional exponents according to the general exponential release equation indicated anomalous (non-Fickian) transport in 5-ASA release controlled by a polymer relaxation, erosion and degradation. Biodistribution studies of [(131)I]-5-ASA loaded chitosan-Ca-alginate microparticles, carried out within 2 days after peroral administration to Wistar male rats in which TNBS colitis was induced, confirmed the dominant localization of 5-ASA in the colon with low systemic bioavailability.