(W0930-02-11) Impact of Direct Vs Indirect Simulation on Material Strength and Deformation Parameters

Purpose: The aim of the present investigation was to investigate the impact of compaction conditions executed with a direct simulation [PRESSTER Compaction Simulator(CS)] and indirect simulator (STYL’One Compaction Simulator) on the material deformation and strength parameters (1).

Methods: Four model materials such as predominantly plastic (Vivapur® 102), elastic (Starch 1500®), low fragmenting (SpheroLac® 100), and high fragmenting (Emcompress®) were selected to evaluate material deformation and material strength using direct and indirect simulation (2). A generated continuous compression profile was utilized to compute material deformation and material strength by ‘in-die’ Heckel analysis (2) and compression modulus (3) methodology. All model materials were compressed at 500 mm/s compression speed and ~100 mm compression pressure using 10 mm flat faced punches. The particle volume of all material was kept constant (0.1913 cm³). A rise time, fall time, and dwell time associated with compaction cycle generated from the direct and an indirect simulation was calculated as per method described in the literature (4). A rise time is the time from 10% of peak force to 90% of peak force. Fall time is the time from 90% of peak force to 10% of peak force. Dwell time is the time from 90% of peak on the rise to 90% of peak on the fall. A compression and decompression energies were calculated by computing area under curve with trapezoid rule. Additionally, compaction force kinetics, compression and decompression energy kinetics were calculated by using time associated with respective compaction cycle.

Results: A comparison of a rise time, a fall time, and a dwell time associated with 500 mm/s linear velocity executed with PRESSTER and 500 mm/s vertical velocity associated with STYL’One is given in Figure 1A. PRESSTER CS rise time, dwell time, and fall time was ~4 to 6.5 times higher than STYL’One CS. It means that the compression speed associated with the former one is ~4 to 6.5 times slower than the later ones. As expected, the compaction force kinetics associated with PRESSTER is ~4 to 6.5 times greater (Figure 1B), while compression and decompression energy kinetics are ~4 to 6.5 times lower than STYL’One CS (Figure 1C, and 1d). Certainly, slower speed associated with PRESSTER CS could provide better material deformation (5). Compression energy, decompression energy, Heckel YPpl, and compression modulus values derived with PRESSTER and STYL’One showed expected same trend for four model materials. The computed compression and decompression energy values with PRESSTER were low and high as compared to those computed STYL’One compaction cycle data. Heckel YPpl and compression moduli values of four model materials evaluated with PRESSTER were lower and higher than those measured with STYL’One compaction simulator. This could be attributed to resulting slower speed associated with linear velocity of PRESSTER compaction simulator. A slow speed provides better material deformation during compression as compared to fast compression speed (5).

Conclusion: Compaction simulation data obtained with direct simulator and indirect simulator showed the same trends of material deformation, material strength, and energy values for four model materials. However, the absolute values of these parameters are different. One of the key reasons is that translation of executed compression speed in direct and indirect simulation are completely different. Executed compression speed with direct simulation due to linear displacement like actual rotary presses resulted in ~4 to 6.5 times slower (depending on the test material) than that executed with indirect simulator. In future studies, this compression speed translation will be considered while designing studies to provide direct comparison of material deformation and strength values.

References: 1. https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/usp-nf-notices/C1245_compaction-simulation.pdf Accessed on 07/03/2025.
2. Haware RV, Tho I, Bauer-Brandl A. Application of multivariate methods to compression behavior evaluation of directly compressible materials. European Journal of Pharmaceutics and Biopharmaceutics. 2009;72(1):148-55.
3. Patel DB, D. PV, Yash P, C. SJ, Robert S, and Haware RV. Compression–decompression modulus (CDM) – an alternative/complementary approach to Heckel’s analysis. Pharmaceutical Development and Technology. 2022;27(7):805-15.
4. Bubb G. Tablet Press Instrumentation in the Reaserch and Development Environment. In: Augsburger L, Hoag, S. W. , editor. Pharmaceutical Dosage Form: Tablets. 3: Taylor and Francis Group; 2008. p. 49-83.
5. Roberts RJ, Rowe RC. The effect of the relationship between punch velocity and particle size on the compaction behaviour of materials with varying deformation mechanisms. J Pharm Pharmacol. 1986;38(8):567-71.

Figure 1 Kinetic evaluation of compaction cycles associated with PRESSTER and STYL'One compaction simulator at 500 mm/s compression speed (A) Normalized PRESSTER to STYL’One compaction cycle parameters; (B) Compaction force kinetics (kN/mS); (C) Compression energy kinetics (kN.mm/mS); and (D) Decompression energy kinetics (kN/mS)

Figure 2 Derived (A) Compression energy; (B) Decompression energy; (C) Material deformation [‘In-die’ Heckel Yield Pressure of Plastic Deformation (YPpl)]; (d) Material strength [Compression Modulus (CM)] parameters from continuous compression profiles obtained with direct simulation (Presster) and indirect simulation (STYL'One CS)