ABSTRACT:
The aim of the present research work was to formulate microcapsules for rate controlled oral delivery of aceclofenac, using cellulose acetate phthalate (CAP) and ethyl cellulose (EC) as release retardant, and to evaluate the physicochemical properties. ‘Polymer deposition by emulsion-solvent evaporation’ technique was employed to produce microcapsules with CAP alone and with different proportions of CAP and EC, using acetone to dissolve the polymers. The formulations were characterized in terms of particle size, morphology, drug loading, entrapment efficiency, nature of flow and drug release. Infrared spectra and differential scanning thermograms confirmed the compatibility of drug with excipients and formulation process. Microcapsules were uniform, spherical, discrete and free flowing with the particle size varying from 397.32 to 526.06 µm. Average particle size increased with increase in proportion of polymer. High drug loading (19.12% to 42.84%) and entrapment efficiency (76.48% to 85.68%) were achieved, both the parameters decreasing with increasing fraction of polymer. The results of powder flow parameters like angle of repose, bulk density, tapped density, compressibility index and Hausner ratio confirmed that the powder was free flowing to enable direct capsule filling. The rate of drug release from microcapsules was found to be inversely related to the proportion of polymer. Substitution of a fraction of CAP with EC further slowed down the drug release rate, but the drug release was above 80% after 8 h. The drug release was dependent on concentration of aceclofenac in the core, with super case II transport mechanism. Delayed controlled release microcapsules of aceclofenac were successfully developed using ethyl cellulose and cellulose acetate phthalate, suitable for oral delivery.