Microencapsulation of ibuprofen and Eudragit RS 100 by the emulsion solvent diffusion technique.
ABSTRACT The emulsion solvent diffusion was employed to prepare modified release microspheres of ibuprofen. The technique was optimised for the following processing variables: the absence/presence of baffles in the reaction vessel, agitation rate and drying time. Thereafter, the influence of various formulation factors on the microencapsulation efficiency, in vitro drug release and micromeritic properties was examined. The variables included the methacrylic polymer, Eudragit(R) RS 100, ibuprofen content and the volume of ethanol used during microencapsulation. The results obtained were then interpreted on a triangular phase diagram to map the region of microencapsulation, as well as those formulations that yielded suitable modified release ibuprofen microspheres.
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ABSTRACT: In order to evaluate the wall forming and sustained release potential of the resin of Boswellia papyrifera in diclofenac sodium microcapsules, different formulations were prepared by the emulsion solvent evaporation method at varying polymer to drug ratios. It was found that formulations with polymer to drug ratio ranging from 2:1 to 5:1 resulted in microcapsules as confirmed from optical microscopy observations. The effects of other variables such as stirring rate, temperature and volume of dispersed phase, on characteristics of microcapsules were also studied. Preliminary studies revealed that the polymer to drug ratio and stirring rate are the primary factors which affect the response variables (encapsulation efficiency and release rate). Thus, central composite design (CCD) was employed to optimize the encapsulation efficiency and release rate with respect to polymer to drug ratio and stirring rate. Accordingly, the central composite design provided an optimum region with an encapsulation efficiency of 27.24 % and release rate of 26.76 h-1/2 at 3.7:1 polymer to drug ratio and 1200 rpm stirring rate. The optimum formulation provided discrete, spherical and freely flowing microcapsules. The in vitro drug release exhibited minimum burst release with sustained release for 12 h. Kinetic study showed the optimized formulation followed Higuchi square root kinetic model with non-Fickian diffusion mechanism. FT-IR analysis indicated that there is no incompatibility between diclofenac sodium and the resin of B. papyrifera. Thus, the resin of B. papyrifera could be a potential alternative wall material for microencapsulation. Keywords: Olibanum resin, diclofenac sodium, microcapsules, central composite design, release kinetics.International Journal of Pharmacy and Pharmaceutical Sciences 12/2013; 6(1):827-837. · 1.59 Impact Factor
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ABSTRACT: Abstract Aim: In order to avoid gastric irritation caused by tolmetin sodium (TS), gastro resistant Eudragit® S 100 microsphere formulations were prepared with the emulsion/solvent diffusion method. Materials: Considering the high water solubility of the TS molecule, the effects of the presence of inorganic salt (NaCl, NaBr and KH2PO4; 0.1 M and 1.0 M) in external phase and external phase pH on the encapsulation efficiency were evaluated. Results: Percentage yield value was found to vary between 55.8% and 72.1%. Improvement in encapsulation efficiency was determined by increasing concentrations of NaCl, NaBr and KH2PO4. The microspheres were observed to have a spherical shape and the measured particle size values varied between 52.1 and 81.5 µm. The released amounts of the drug were found to be low as the inorganic salt concentrations increased. Conclusion: Conclusively, drug release in stomach pH was significantly prevented by the microspheres prepared using Eudragit® S 100 polymer, and these formulations are considered to be a model for other orally administered drugs with similar problems.Drug Development and Industrial Pharmacy 04/2013; · 1.54 Impact Factor
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ABSTRACT: Objective: The present study is aimed to investigate the resin from local olibanum (Boswellia papyrifera) as a wall material for microencapsulation using diclofenac sodium as a model drug. Methods: Microcapsule formulations were prepared by solvent evaporation method with varying polymer to drug ratio, stirring rate, temperature and dispersed phase volumes and their effects on percentage yield, particle size, encapsulation efficiency and release rate were evaluated. Results: The preliminary experiments revealed that the polymer to drug ratio and stirring rate significantly affect both the encapsulation efficiency and release rate while the other factors only affect one of the responses. Therefore, the effects of polymer to drug ratio and stirring rate on the encapsulation efficiency and release rate of the microcapsules were further studied and optimized by central composite design. The optimal conditions were obtained at 3.7:1 polymer to drug ratio and 1200 rpm stirring rate. Under these conditions, the encapsulation efficiency and release rate were 26.45 % and 27.87 h-1/2, respectively. The optimum formulation also provided discrete, spherical and freely flowing microcapsules. The in vitro drug release exhibited minimum burst release with sustained release for 12 h. The kinetic study showed the optimized formulation followed Higuchi square root kinetic model with non-Fickian diffusion release mechanism. Conclusion: The results of this study showed that the resin of B. papyrifera could be used as a potential alternative wall material for microencapsulation. Keywords: Olibanum resin, Diclofenac sodium, Solvent evaporation method, Microcapsules, Encapsulation efficiency, Controlled release, Release kineticsInternational Journal of Pharmacy and Pharmaceutical Sciences 12/2013; 6(1):827-837. · 1.59 Impact Factor