EVALUATION OF AQUEOUS ENTERIC-COATED GRANULES PREPARED BY MOISTURE CONTROL METHOD IN TUMBLING FLUIDIZED-BED PROCESS

Based on the moisture control system developed previously, we have alr eady reported that the operational moisture content during aqueous pol ymeric coating by a type of fluidized bed should be controlled for a b etter coating efficiency. In this paper, effects of operational moistu re content and agitator rotational speed on the properties of granules prepared by the aqueous polymeric coating were investigated experimen tally, and optimization of this process was conducted. Core granules ( mean diameter 600 mum) containing a model drug, pigment Blue No. 1, we re coated with the aqueous dispersion of enteric polymer (Eudragit L30 D) by the tumbling fluidized bed with controlling the operational mois ture content. The coated granules were evaluated by dissolution tests in JP 1st (pH 1.2) and 2nd fluid (pH 6.8) and by agglomeration tendenc y. Film thickness and specific surface area of the granules were exami ned to discuss the film forming process. Based on the evaluation, effe cts of the operational variables on the drug release rate and agglomer ation tendency were investigated. It was found that the drug release r ate was suppressed with increase in moisture content at any rotational speed in the JP 1st and 2nd fluid, and the agglomeration tendency was prevented with increase in moisture content and agitator rotational s peed. It was concluded from the results that the aqueous coating with the enteric polymer by the tumbling fluidized bed process should be ca rried out under a condition of moisture content between 12 and 14% wit h agitation below 5 rps.