Combining solid lipid-nanoparticles in Alginate coating formulation to prepare enteric-released Diclofenac pellets

In the trend of using natural-resource substances in current pharmaceutical industry, alginate (ALG) film was used to coat tablets. To further develop ALG film-coating, solid lipid nanoparticles of cetearyl alcohol (ACS) or glycerol monostearate (GMS) were added in the coating formulation, applying to the diclofenac sodium (Na-D) pellet. Na-D pellets were prepared by the extrusion-spheronization method. Coated pellets were characterized with anti-moisture and acidic-resistant, and dissolution properties. Also, coating morphology was observed by microscopy and scanning electron microscopy (SEM); difference-scanning-calorimetry (DSC) and infrared (IR) spectroscopy were used to characterize the coating structure. The results showed that the nanoparticles were uniformly distributed into ALG structure. Interestingly, lipid nanoparticles enhaced the flexibility of the film, in which GMS nanoparticles improved the film-formed process (significantly lowering glass transition temperature). Regarding functions of the coating membrane, the moisture resistance and acid resistance of Na-D pellets increased only when nanolipids were present in the membrane.