Emulsification/internal gelation has been suggested as an alternative to extrusion/external gelation in the encapsulation of several compounds including non-steroidal anti-inflammatory drugs such as diclofenac sodium. The objective of the present study was a trial to formulate diclofenac sodium as controlled release microparticles that might be administered once or twice daily. This could be achieved via emulsification/internal gelation technique applying Box-Behnken design to choose these formulae. Box-Behnken design determined fifteen formulae containing specified amounts of the independent variables, which included stirring speed in rpm (X1), drug:polymer ratio (X2) and the surfactant span 80% (X3). The dependent variables studied were cumulative percent release after two hours (Y1), four hours (Y2) and eight hours (Y3). The prepared microparticles were characterized for their production yield, sizes, shapes and morphology, entrapment efficiency and Diclofenac sodium in vitro release as well. The results showed that the production yield of the prepared diclofenac sodium microparticles was found to be between 79.55% and 97.41%. The formulated microparticles exhibited acceptable drug content values that lie in the range 66.20-96.36%. Also, the data obtained revealed that increasing the mixing speed (X1) generally resulted in decreased microparticle size. In addition, scanning electron microscope images of the microparticles illustrated that the formula contains lower span concentration (1%) in combination with lower stirring speed (200 rpm) which showed wrinkled, but smooth surfaces. However, by increasing surfactant concentration, microspheres' surfaces become smoother and slightly porous. Kinetic treatment of the in vitro release from drug-loaded microparticles indicated that the zero order is the drug release mechanism for the most formulae.

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Piroxicam is a potent nonsteroidal anti-inflammatory drug associated with many side effects when taken orally. An attention was paid in this work to formulate and characterize piroxicam containing polymer films for dermal use. The used polymers were Eudragit types namely Eudragit RL100, RS100, L100 and Eudragit S100. In this study, medicated films consisting of drug and carrier were prepared. The carrier consisted of one or two polymers. The physicochemical characterization was done by IR spectroscopy, DSC and X-Ray diffractometry for both piroxicam polymeric films and their corresponding physical mixtures as well as the untreated drug and polymer powders to investigate the drug polymer interaction. The results indicate presence of molecular interactions between piroxicam and both Eudragit L100 and Eudragit S100 and no interactions were found between piroxicam and Eudragit RL100 or Eudragit RS100. In-vitro drug release from Eudragit films was studied. It is found that the drug release from hydrophilic polymers is faster than that from hydrophobic ones.

In a trial to delay the release rate of diclofenac sodium from alginate coated microcapsules, the use of a copolymer was suggested. Mixtures of polymers can have a significant properties than that of individual polymer to achieve sustained release microcapsules. On considering the negative charge of alginate and its ability to form polyionic complexes with a lowered tendency of erosion at higher pH value, a cationic polymer was seeked. Chitosan (CS) was the one of choice due to the similarity of the saccharide structures of chitosan and alginate that offers greater interaction between the two polymers and stronger inter-chains reactions relative to that between alginate and branched polymers such as polylysine. The microcapsules prepared using 0.1 and 0.25% (CS) were spherical in shape while 0.4% (CS) formed microcapsules having rounded heads and tapered tails. The change in chitosan concentration had a non-significant effect on the particle size, the yield and the drug loading efficiency. The releaser ate of diclofenac sodium from microspheres showed a pHdependent profile and was affected by chitosan coating. The release rate of diclofenac sodium from chitosan coated alginate microcapsules at pH 7.4 was found to be faster than its release at pH 1.2. These results suggest this coating method to protect diclofenac sodium under acidic conditions and to permit a complete but controlled release of diclofenac sodium.

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