EFFECT OF STEARIC-ACID PARTICLE-SIZE ON SURFACE CHARACTERISTICS OF FILM-COATED TABLETS

Raw material specifications are vital for many excipients used in the manufacture of tablets. Stearic acid powder is widely used in the phar maceutical industry as a tablet lubricant. This study shows that the v ariation in particle size of stearic acid not only affects die wall lu brication properties (ejection force) but also affects surface charact eristics of film-coated tablets. A coarser grade of stearic acid can d islodge from tablet surfaces during the film-coating process leaving p it marks, whereas a finer grade of stearic acid (less than 100 mesh) r esults in film-coated tablets having very smooth surfaces. The mechani sm of pitting on the tablet surface is described. A specification for stearic acid particle size to overcome this problem is suggested.