EXPERIENCES WITH UNIT-TO-UNIT VARIATIONS IN TABLETS

The literature reports on the subject of interunit dosage and weight variations of tablets indicate that past studies were mainly concerned with analyzing the finished product to detect gross departures from the desired quality. These studies, however, were cognizant of the several stages of manufacture before the compression step could contribute to the end tablet variability. In this investigation, the variability in several stages of tablet manufacturing (dry mixing, granulating, lubricating, and tableting) was evaluated for a particular tablet formulation. The importance of employing correct sampling procedures to obtain random samples to be used for the accurate estimation of the sources of variability and product uniformity is illustrated. The relationship that exists between tablet weights and drug concentration was determined. Since systematic sampling is commonly employed in the in-process control of tableting operations, the information that can be gained from this type of sampling procedure and random sampling is presented and discussed.