Ethylcellulose-Based Matrix-Type Microspheres: Influence of Plasticizer RATIO as Pore-Forming Agent |
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Authors: | C Tuba Sengel-Turk Canan Hascicek Nursin Gonul |
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Institution: | (1) Faculty of Pharmacy, Department of Pharmaceutical Technology, Ankara University, Tandogan, 06100 Ankara, Turkey; |
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Abstract: | In this study, ethylcellulose (EC)-based microsphere formulations were prepared without and with triethyl citrate (TEC) content
of 10% and 30% by water-in-oil emulsion-solvent evaporation technique. Diltiazem hydrochloride (DH) was chosen as a hydrophilic
model drug and used at different drug/polymer ratios in the microspheres. The aim of the work was to evaluate the influence
of plasticizer ratio on the drug release rate and physicochemical characteristics of EC-based matrix-type microspheres. The
resulting microspheres were evaluated for encapsulation efficiency, particle size and size distribution, surface morphology,
total pore volume, thermal characteristics, drug release rates, and release mechanism. Results indicated that the physicochemical
properties of microspheres were strongly affected by the drug/polymer ratio investigated and the concentration of TEC used
in the production technique. The surface morphology and pore volume of microspheres significantly varied based on the plasticizer
content in the formulation. DH release rate from EC-based matrix-type microspheres can be controlled by varying the DH to
polymer and plasticizer ratios. Glass transition temperature values tended to decrease in conjunction with increasing amounts
of TEC. Consequently, the various characteristics of the EC microspheres could be modified based on the plasticized ratio
of TEC. |
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