GASTRO-RETENTIVE FLOATING SYSTEMS PRODUCED BY IONOTROPIC GELATION FOR ENHANCED ORAL DRUG BIOAVAILABILITY
Lidiane Ruiz Tonon Queiroz, Carine Santana Ferreira, Patrícia Severino*, Eliana B. Souto, Newton Andreo Filho and Marco Vinícius Chaud
ABSTRACT
The purpose of this study was to develop controlled-release granules for floating gastro-retentive systems. The granules were obtained by ionotropic gelation method between sodium alginate and calcium chloride, from a previously prepared oil-in-water emulsion. Azithromycin, clarithromycin, prednisone, fluconazole and ranitidine were used as model drugs. The physicochemical characterization of the obtained granules was based on the analysis of the loading capacity for the selected drugs, the floating time and lag time, and the sphericity of the beads. Wide Angle X-ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC) were run for the assessment of the polymorphism of the drugs. A dissolution test was carried out for the evaluation of the release profile of the drugs. Our results demonstrate that the fluctuation of the granules was immediate and the fluctuation time was greater than 24 hours. The loading capacity was influenced by the lipophilicity of the drugs. The low loading capacity of ranitidine was attributed to the hydrophilicity of the drug and to oxidative degradation. DSC and WAXD analyses indicate azithromycin, clarithromycin and prednisone suffered polymorphic changes upon loading by ionotropic gelation. A controlled release profile was observed for azithromycin and clarithromycin, while a release rate reduction was observed for fluconazole and prednisone. From the tested drugs, ionotropic gelation between sodium alginate and calcium chloride, from an oil-in-water emulsion was shown to be an effective strategy for developing floating gastro-retentive systems for azithromycin and clarithromycin.
Keywords: Gastro-retentive floating granules, ionotropic gelation, azithromycin, clarithromycin, prednisone, fluconazole, ranitidine.
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