Surface treatment of acetylsalicylic acid with water-soluble lubricants ina fluid bed coater by the Wurster method

The Strea-1 fluid bed coater with the Wurster column can be used for the pr oduction of a lubricant coat on crystal surfaces. The surface treatment of acetylsalicylic acid (ASA) crystals was examined in a Wurster fluid bed sys tem with two water-soluble lubricants (Lutrol(R) F68 and Carbowax(R) 6000). The influence of the coating process on the flowability, the tablettabilit y, the lubricant sensitivity ratio and the rate of dissolution of ASA cryst als was studied. The results were compared with the corresponding parameter s for unlubricated ASA crystals. In comparison with the unlubricated sample , the lubricated crystals have good flow properties and tablettability. The wetting effects of the lubricant coats are very favourable for the rate of dissolution of ASA from capsules and for the tablet disintegration time. 0 .5% of either lubricant was sufficient to achieve good parameters, but 1% o f Lutrol F68 could not be suggested for a coating process.