Simple preparation of coated resin complexes and their incorporation into fast-disintegrating tablets.

Even though ion-exchange resins are good drug carriers to get sustained release properties, it may not be good enough only with themselves. For further sustained release effect, a diffusion barrier or coating on the resins' surface can be utilized. Initially, microencapsulation using a w/o/w double emulsion method was used to apply ethylcellulose (EC) onto the drug/resin complexes. Typical pharmaceutical waxes can be alternative materials to delay the drug release from the complex. After the coating, the coated resin particles were incorporated into fast-disintegrating tablets to get an idea regarding the effects of wet granulation and compression on the release. Among the different grades of ECs tested (Ethocel 20, 45, and 100), more viscous EC resulted in better morphologies and sustained release effects. Because the drug release rate was significantly dependent on the coating level, the release rate can be modified easily by changing different levels of the coating. The drug release rate was also strongly dependent on the granulation and compaction process as the coated particles were incorporated into the tablet dosage form. Among the tested waxes, stearic acid had an effect on the sustained release together with lubrication and wetting properties. Even though microencapsulation or wax coating may not be practical for real manufacturing, the results may give valuable information how to formulate sustained release dosage forms and their properties on the tablet preparation.