In-vitro studies of enteric coated diclofenac sodium-carboxymethylcellulose microspheres

Microspheres containing diclofenac sodium (DS) were prepared using carboxymethylcellulose (CMC) as the main support material (1.0, 2.0, 3.0% (w/v)) and aluminium chloride as the crosslinker. Drug to polymer ratios of 1:1, 1:2 and 1:4 were used to obtain a range of microspheres. The microspheres were then coated with an enteric coating material, Eudragit(R)S-100, with aqueous solution concentrations of 10 and 20% (w/v). Encapsulation efficiency, % yield value, particle sizes and in-vitro dissolution behaviour were investigated. The surface of the enteric coated microspheres seemed to be all covered with Eudragit(R)S-100 from scanning electron microscopy observation. It was also observed that increasing the CMC concentration led to an increase in the encapsulation efficiency, % yield value and particle size and decreased the release rate. Eudragit(R)S-100 coating did not significantly alter the size but the release rate was significantly lower even when the lower concentration solution was used.