Poloxamer based Urapidil Loaded Chitosan Microparticle in Approach to Improve the Mechanical Strength by Tensile Strength and Entrapment Determination

Background: The literature review has highlighted the issues related to the poor mechanical strength of chitosan-based microparticles. In an attempt to resolve the drawbacks, the microparticles were prepared with a suitable combination of poloxamer-188 (pluronic) and chitosan-based hydrogels. Objective: The current study dealt with urapidil-loaded chitosan microparticles incorporating chitosanbased hydrogels and small polyanionic electrolytes. The mechanical strength was ascertained by entrapment efficiency and texture analyzer. Methods: Chitosan-based hydrogels and the combination of poloxamer and further microparticles were prepared by the counter-ion aggregation technique in a polyanionic electrolyte medium (20 % w/v). During the preparation, poloxamer was incorporated to improve the mechanical strength, which was ascertained in terms of adhesive strength (tensile strength) by texture analyzer and entrapment efficiency. The prepared microparticles were also subjected to micrometric studies, swelling index, surface morphology study, drug-polymer interaction study, and zeta analysis. Results: A remarkable increase in entrapment efficiency (maximum of 78.56 % from SSP4) was observed with the progressive increase in poloxamer-188. In addition to that, the adhesive strength was also studied by a texture analyzer for all microparticles. Sodium citrate-based products exhibited superior adhesive strength values than sodium sulfate- and sodium tripolyphosphate-based products, indicating the significance of incorporating poloxamer-188. A significant finding was also recorded for the swelling properties at microenvironmental pH attributed to polyanions. It was observed that sodium TPP microparticles continued to swell in a phosphate buffer of pH 6.8. Zeta value was found to be maximum with -5.2 mV; however, it could further be improved by adding electrolytes. TPP4 showed a comparatively larger particle size of 8.07 μm. Polydispersity index value revealed homogenous dispersion of microparticles. SEM study revealed prominent porous surfaces for sodium tripolyphosphate microparticles. Conclusion: The study revealed that the addition of poloxamer-188 improved the mechanical strength, identified by entrapment efficiency and texture analysis. SCP4 microparticle was found to be the best formulation among all.