TABLET COATING METHODS FOR VERY SMALL BATCHES AND THEIR SUITABILITY FOR SCALING-UP

Three different laboratory-scale coating devices were tested for thei r performance in terms of coating very small batches of solid dosage f orms. The need for this study arose from a new film-forming material f or colon-targeting which is available only in very small amounts. Part icular attention should be paid to the subsequently planned scaling-up procedures. The following properties should be achieved: Homogeneous and smooth surfaces, as well as an overall equal film thickness obtain ed under controlled spraying rates of the coating solution, and determ ined flow-rates of the drying air. The obtained results show that all three units are principally suitable. The Huttlin HKC provides a uniqu e small, variable working segment by subdividing the spherical coating chamber by installing two vertical partition walls. In such reduced c oating segments very similar coating conditions, and practically simil ar material movements were observed, in spite of reducing the batch si ze as far as possible.