Preparation and Characterization of Gastro-retentive Sustained Release Microcapsules of Salbutamol Sulphate

The objective of this study was to prepare gastro-retentive microcapsules using solvent evaporation method containing salbutamol sulphate. The effect of various viscosity grades of ethylcellulose (EC) on In vitro drug release and buoyancy was evaluated. The influence of formulation factors (stirring speed, Drug: EC ratio, various viscosity grades of EC) on particle size, encapsulation efficiency, in-vitro release characteristics was studied. FT-IR and DSC studies revealed no interaction between drug and EC. The yields and the encapsulation efficiencies were high for all microcapsule formulations. Floating lag time was zero for all microcapsules prepared with EC 7 cPs whereas EC N50 based microcapsules did not show buoyancyl. EC 18-22 cPs based microcapsules showed zero floating lag time for formulations with drug to EC ratio of 1:1 and 1:1.5 but 1:2 ratio did not exhibit buoyancy. Stirring speed was inversely related to the size of the microcapsules. In-vitro release studies revealed that the drug release was sustained upto 12 h for microcapsules prepared with EC 18-22 cPs and EC N50 whereas EC 7 cPs based microcapsules could not sustain the release for more than 6 h. Stability studies as per ICH guidelines revealed no significant change in drug entrapment efficiency, in vitro buoyancy and in vitro drug release. Hence incorporation of optimum concentration of EC 18-22 cPs (F5) in the formulation of microcapsules by solvent evaporation method proved to be an effective method in achieving desired release behavior and buoyancy.