In this study, orlistat liposomes were developed and characterized for the physical as well as chemical parameters by ethanol injection method. Formula optimization studies were utilized to investigate the impact of different molar ratios of orlistat drug, soya phosphatidylcholine and cholesterol on physical appearance, pH, density, % drug entrapment efficiency, particle size, polydispersity index and zeta potential. Process optimization studies were also performed to comprehend the effect of variable stirring time, sonication time and centrifugation time on the physical and chemical features. Digital micrographs revealed that the liposomes were in spherical shape. The optimized formulations have about 90.6±0.3% (F30) and 89.0±0.2% (F31) drug entrapment efficiency. Sonication of liposomes was done by probe tip sonicator. Vesicle size, shape and entrapment efficiency were determined by dynamic light scattering, digital microscopy and centrifugation method, respectively. Results showed that high API and cholesterol content resulted in increased entrapment efficiency. Particle size of vesicles was in the nanometers range and uniform in size with no high variability. Zeta potential values of the optimized formulations demonstrated that the liposomes obtained in this study were a dynamic stable system. Effect of alternate method was also seen, thin film hydration method on the physical characteristics as well as the drug entrapment efficiency of orlistat liposomes. Physical appearance was very thin and marginally turbid consistency. No any drug entrapment was observed with the thin film hydration method.
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