Surface Treatment of acetylsalicylic acid with Lubricants by the Wurster method

Surface treatment of acetylsalicylic acid (ASA) crystals was examined in a Wurster fluid bed system with water-soluble and water-insoluble lubricants. The influence of the coating process on the flowability, the compressibili ty and the dissolution rate of the crystals was studied, and the results we re compared with the corresponding parameters of ASA crystals professed by a conventional (mixing) method, The coating materials were Carbowax(R) 6000 as water-soluble and stearin as water-insoluble lubricant. The control sam ple was unprocessed (commercial) ASA crystals, The Strea-1 fluid bed coater with the Wurster column could be used for the production of a lubricant co ating on crystal surfaces, The coated crystals, in comparison with mixed sa mples, had very good compactibility, cohesivity and compressibility values, Their lubrication coefficient was higher and the friction work was less th an those of mixed crystals. The dissolution of the active agent could be re gulated by the lubricant coat, The rate of dissolution of ASA was primarily promoted by a film coat of Carbowax(R) 6000 from a capsule.