Quantitative assessment of factors contributing to mottling of colored tablets I: manufacturing variables

By using a recently developed method for quantifying the degree of mottling of colored tablets, the effects of manufacturing variables such as the method and temperature of granule drying, granule size, and compaction pressure were investigated. Tablets of dibasic calcium phosphate colored with FD&C Blue No. 1 dye were used. Drying temperature had little effect, but the method of granule drying, granule size, and compaction pressure were major influences on mottling. Mechanisms to explain these results, based on the migration of dye during the drying process, are proposed.