Abstract
Lubricants are an important material in the production of tablets in industrial scale by compression because they supress adhesion to punches and die and inprove powder flowability during compression. Although insoluble material, such as magnesium stearate, is the most popular lubricant for practical use, we applied a soluble material: sodium lauryl sulfate (SLS) to direct compression method as a lubricant, and investigated the effect of humidity on the tableting compression properties. Spray-dried SLS (S-SLS) and recrystallized SLS (R-SLS) were used as lubricants. Physicochemical properties of S-SLS were significantly different from those of R-SLS. R-SLS absorbed water at a relative humidity (RH) higher than 20% at 25°C, whereas the water adsorption of S-SLS occured at a RH higher than 60%. The bulk powder for tableting compression test was prepared by mixing spray-dried lactose and 0.1% SLS. The compression and ejection processes were evaluated by measuring compression and ejection energy during tableting process. The tableting compression processes of S-SLS and R-SLS were not affected by the storage humidity of SLS. The tablet ejection energy of wetted S-SLS was significantly lower than that of dried S-SLS, but those of R-SLS were almost the same.
