Tablet press instrumentation

The use of compaction simulators was first reported in 1976. Since then, a variety of simulators have been developed. Hydraulic simulators, as well as mechanical simulators, are available to characterize raw materials, drug substances, and formulations, as well as to predict material behavior on scale-up. The appeal of simulators is due to the fact that they purport to provide the same compaction profile as experienced on a tablet press while using only gram or even milligram quantities of powders. Compaction simulators can achieve high speeds, as would be experienced on a production tablet press, and can be instrumented to measure a variety of parameters, including upper and lower punch force, upper and lower punch displacement, ejection force, radial die wall force, take-off force, etc. Summaries on the uses of simulators and tablet press instrumentation can be found in (19,20). 

Much of the information about compaction can be attributed to the early work in tablet press instrumentation and publications in the general area identified as the physics of tablet compression. For the interested reader, a review of the early history of that work has been published elsewhere [2]. 

In general, one should be aware that tablet press instrumentation involves the use of strain gauges or piezoelectric transducers to provide a voltage signal proportional to the force applied for the compaction operation. Let us say we can measure forces, such as those applied to the granulation by the punches, that applied to the die wall, that required for tablet ejection, etc. With tlie use of other transducers we can also measure distance. With the measurement of force and distance, we can calculate work, energy, etc. 

There are several uses of tablet press instrumentation in the scale-up process itself. One of these involves obtaining a sample of the scale-up batch and compacting that sample on the pilot-plant or research instrumented tablet press on which the formulation has been previously evaluated. Similarity of the fingerprint or the various research plots (Heckel, force-displacement, radial vs. axial plots) is evidence that the scale-up batch is similar to the previously evaluated research batch [2]. 

This article is designed to facilitate the understanding of the general principles of tablet press instrumentation and the benefits thereof by the formulators, process engineers, validation specialists, and quality assurance personnel, as well as production floor supervisors who would like to understand the basic standards and techniques of getting information about their tableting process. 

TABLET PRESS INSTRUMENTATION FOR PRODUCT AND PROCESS DEVELOPMENT... 

Selected excerpts and figures from M. Levin, Tablet Press Instrumentation for Product Development, Process Scale-Up and Production Quality Control, Education Anytime, CD-ROM Short Course, AAPS 1999 are reprinted with permission. 

Tablet Evaluation Using Near-Infrared Spectroscopy / 3630 Tablet Formulation / 3641 Tablet Manufacture / 3653 Tablet Manufacture by Direct Compression / 3673 Tablet Press Instrumentation / 3684 Tablet Testing / 3707 Technology Transfer Considerations tor Pharmaceuticals / 3717...

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