Evaluation of Batch-To-Batch and Manufacturer-To-Manufacturer Variability in the Physical Properties of Talc and Stearic Acid

Abstract Magnesium stearate, talc and stearic acid are commonly used as lubricants in tablet formulations. Many studies on the batch-to-batch and manufacturer-to-manufacturer variability in the physical properties and lubricity of magnesium stearate have been reported in the literature. However, very few similar studies have been reported on talc or stearic acid. In this study, physical properties such as particle size, specific surface area, thermal behavior, moisture content, density, and particle shape and morphology of talc and stearic acid batches obtained from several manufacturers were examined. There was little batch-to-batch variability observed in the talc and stearic acid batches obtained from various manufacturers; however, differences in the particle size and specific surface area were seen in the two types of talc, USP samples obtained from one manufacturer. The scanning electron microscope photomicrographs of the stearic acid samples obtained from various manufacturers also showed some differences in the amount of flakes attached to the spherical particles.