1994 Volume 42 Issue 3 Pages 663-667
Based on the moisture control system developed previously, we have already reported that the operational moisture content during aqueous polymeric coating by a type of fluidized bed should be controlled for a better coating efficiency.In this paper, effects of operational moisture content and agitator rotational speed on the properties of granules prepared by the aqueous polymeric coating were investigated experimentally, and optimization of this process was conducted. Core granules (mean diameter 600 μM) containing a model drug, pigment Blue No. 1, were coated with the aqueous dispersion of enteric polymer (Eudragit L30D) by the tumbling fluidized bed with controlling the operational moisture content. The coated granules were evaluated by dissolution tests in JP 1st (pH 1.2) and 2nd fluid (pH 6.8) and by agglomeration tendency. Film thickness and specific surface area of the granules were examined to discuss the film forming process. Based on the evaluation, effects of the operational variables on the drug release rate and agglomeration tendency were investigated. It was found that the drug release rate 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 speed. It was concluded from the results that the aqueous coating with the enteric polymer by the tumbling fluidized bed process should be carried out under a condition of moisture content between 12 and 14% with agitation below 5 rps.
