preparation and determination of drug-polymer interaction and in-vitro release of mefenamic acid microspheres made of cellulose acetate phthalate and/or ethylcellulose polymers

the objective of this study was to formulate and evaluate the drug-polymer interaction of mefenamic acid (ma) using two polymers with different characteristics as ethylcellulose (ec) and/or cellulose acetate phthalate (cap). microspheres were prepared by the modified emulsion solvent evaporation (mese). the effect of drug-polymer interaction was studied for each of microspheres. important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteristics of microspheres, scanning electronic microscopy (sem), powder x-ray diffraction analysis (xrd), and differential scanning calorimetry (dsc). the in-vitro release studies are performed in tris buffer (ph 9) with sodium lauryl sulfate (sls). microspheres containing cap and ec showed 68-97% and 63-76% of entrapment efficiency, respectively. the thermogram x-ray and dsc showed stable character of ma in the microspheres and revealed an absence of drug polymer interaction. the prepared microspheres were spherical in shape and had a size range of 235-436 μm for cap-microspheres and 358-442 μm for ec-microspheres. the results suggest that ma was successfully and efficiently encapsulated; the release rates of matrix microspheres are related to the type of polymer, only when polymers (ec and cap combine with 1 : 1 ratio) were used to get prolonged drug release with reducing the polymers content in the microspheres. data obtained from in-vitro release for microspheres and commercial capsule were fitted to various kinetic models and the high correlation was obtained in the peppas model.