Study of radial die-wall pressure changes during pharmaceutical powder compaction

Abstract

Context: In tablet manufacturing, less attention is paid to the measurement of die-wall pressure than to force–displacement diagrams. Objective: Therefore, the aim of this study was to investigate radial stress change during pharmaceutical compaction. Materials and Methods: The Presster^TM, a tablet-press replicator was used to characterize compaction behavior of microcrystalline cellulose (viscoelastic), calcium hydrogen phosphate dihydrate (brittle), direct compressible mannitol (plastic), pre-gelatinized starch (plastic/elastic), and spray dried lactose monohydrate (plastic/brittle) by measuring radial die-wall pressure; therefore powders were compacted at different (pre) compaction pressures as well as different speeds. Residual die-wall pressure (RDP) and maximum die-wall pressure (MDP) were measured. Various tablet physical properties were correlated to radial die-wall pressure. Results and Discussion: With increasing compaction pressure, RDP and MDP (P < 0.0001) increased for all materials, with increasing precompaction RDP decreased for plastic materials (P < 0.05), whereas with increasing speed MDP decreased for all materials (P < 0.05). During decompression, microcrystalline cellulose and pre-gelatinized starch showed higher axial relaxation, whereas mannitol and lactose showed higher radial relaxation, calcium hydrogen phosphate showed high axial and radial relaxations. Plastic and brittle materials showed increased tendencies for friction because of high radial relaxation. Conclusion: Die-wall monitoring is suggested as a valuable tool for characterizing compaction behavior of materials and detecting friction phenomena in the early stage of development.

• Capping
• compaction simulation
• die-wall instrumentation
• friction
• (pre)compaction pressure
• radial die-wall pressure
• speed

Acknowledgment

The authors would like to express their sincere thanks for the Egyptian ministry of higher education for supporting the study.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.