Introducing a novel gravitation-based high-velocity compaction analysis method for pharmaceutical powders

Abstract

With modern tableting machines large amounts of tablets are produced with high output. Consequently, methods to examine powder compression in a high-velocity setting are in demand. In the present study, a novel gravitation-based method was developed to examine powder compression. A steel bar is dropped on a punch to compress microcrystalline cellulose and starch samples inside the die. The distance of the bar is being read by a high-accuracy laser displacement sensor which provides a reliable distance-time plot for the bar movement. In-die height and density of the compact can be seen directly from this data, which can be examined further to obtain information on velocity, acceleration and energy distribution during compression. The energy consumed in compact formation could also be seen. Despite the high vertical compression speed, the method was proven to be cost-efficient, accurate and reproducible.

Compression Modulus and Apparent Density of Polymeric Excipients during Compression—Impact on Tabletability

“…Overall, the extent of the ER in-die for polymeric and nonpolymeric excipients was in accordance with the literature. Tanner [ 48 ] noted ER in-die values for calcium phosphate grades of 1–5%, lactose grades of 1–6%, microcrystalline cellulose grades of 7–12%, HPMC of 14–17%, and starch grades of 14–18%. The present study determined values in similar ranges for nonpolymeric excipients, e.g., <4% for FlowLac ® 100 and <3% for DI-CAFOS ® A60.…”

Examining mechanical properties of various pharmaceutical excipients with the gravitation-based high-velocity compaction analysis method

“…The high-speed gravitational powder compression analysis method was explained in detail in our earlier work (Tanner et al 2017). The method is based on measuring the movement of a freely falling steel bar and the base of the system with displacement sensors (Keyence LK-H087, Keyence Corporation of America, Itasca, Illinois, USA).…”

“…The method to estimate the internal energy change of samples after each compression was introduced in our previous work (Tanner et. al 2017).…”

“…This work consists mainly of internal energy change of powder/compact, kinetic energy of the base, friction between the machine parts, steel-on-steel heat generation/dissipation, machine deformation, vibration and sound. Internal energy change affiliated with powder compaction consists mainly of bond formation, 270 interparticulate friction, particle-die-wall friction, heat dissipation and microstresses which are partially released right after the compression and partially after ejection which can be seen as both, in-die and out-of-die compact recovery, occur (Tanner et al 2017;Krok et al 2016). Some of the microstresses are generally still present in the compact in-die after compression since compacts tend to recover more of their volume when ejected from the die (Haware et al 2010;Abdel-Hamid 275 and Betz 2011).…”

“…In our previous work, we introduced a gravitation-based high-velocity compaction analysis method 40 for pharmaceutical powders (Tanner et al 2017). In this method, the displacement of a freely falling steel bar is being recorded as it collides with the punch, delivering energy into the powder inside the die.…”