Abstract
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 pH-dependent 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.