The present investigation focuses on the preparation and evaluation of non effervescent multiparticulate gastrobuoyant microballoons of lansoprazole by emulsion solvent diffusion method using hydroxypropyl methylcellulose phthalate for enhanced bioavailability. The solvents used in suitable ratio in the preparation are ethyl alcohol and dichloromethane. Optimization studies were carried out by central composite design to study the influence of process and formulation factors on the efficiency of formulations. All the formulations were found be spherical and discrete entities with free flowability. A considerable extent of drug entrapment was attained at lower polymer concentration at a lower stirring rate maintained at 40°C. The drug encapsulation with in the polymeric crust was found to be 81 % against the predicted 75 %. The sphericity and hollow within the microspheres was confirmed by SEM photography. The micromeritic properties indicated better flowability and packability of the spheres. The average particle size of lansoprazole and the formulation LHPMCP-D1 was found to be 135.64 ± 5.22 and 345 ± 32 µm respectively. The in vitro buoyancy was around 94 % with good floatability upto 12 h. In vitro dissolution profile showed prolonged release of drug upto 92 % over 12 h against the predicted 85 % release with non-Fickian diffusion mechanism of drug release. An acute oral toxicity study was done as per OECD guidelines showed no mortality with normal haematological and biochemical values. Histopathogical studies proved the absence of any toxicity. Pylorus ligation method showed that the mean volume of gastric juice for control, pure drug lansoprazole and LHPMCP-D1 was found to be 6.51 ± 0.199, 4.01 ± 0.133 and 4.3 ± 0.07 ml respectively. Free acidity and total acidity for the optimized formulation was found to be 40.83 ± 1.53 mEq/l/100g and 132± 1.33 mEq/l/100g respectively in comparison to 57.66 ± 2.27 and 180.33 ± 1.14 of control animal, 44.83 ± 1.66 and 134.83 ± 1.424 mEq/l/100g of pure drug. An appreciable rise in the pH 5.50 ± 0.051 of LHPMCP-D1 was indicative of the antiulcer activity of the formulation. Residual solvent analysis for dichloromethane and ethanol by gas chromatography was found to be within the limits as prescribed by ICH guidelines for impurities. Long term and accelerated stability studies showed the integrity of drug without any significant change in the physical properties. Thus lansoprazole microballoons with HPMCP proved to be a novel formulation for controlled drug delivery for better bioavailability and patient compliance.
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