Associations of parameters characterizing the time course of the tabletting process on a reciprocating and on a rotary tabletting machine for high-speed production

Abstract

A series of modern direct-compression excipients with differing mechanisms of deformation and densification, Karion Instant® Pharma, Vivacel® 200, Cellactose®, Tablettose®, and Parmcompress®, after admixing magnesium stearate, have been tabletted (400 mg, 10 mm flat-faced punches) on an eccentric machine, Fette E XI at 43.6 rpm, and on a rotary machine, Fette PT 2090 at 20, 60, and 90 rpm, to graded maximum forces (3, 5, 10, 15 kN, respectively). Force/time (E XI and PT 2090) and displacement/time (E XI) curves were recorded. From the data on the E XI, parameters of a modified Weibull function, slopes of the Heckel function, quotients of partial areas under the curves, and the differences between times of maximum forces and the respective maximum densifications, t diff, were calculated. From the data on the PT 2090, partial areas under the curves for the upper punch, various quotients of these areas, and the peak-offset times, t off, the times of maximum force relative to the middle of the dwell time, t dwell, were calculated. Close associations were found between the area A1 rel during the precompression phase (PT 2090) and the Heckel slope (E XI), between the quotient of partial areas before and after the middle of t dwell (PT 2090) and that of partial areas before and after maximum densification (E XI), and between t off (PT 2090) and t diff (E XI). However, certain materials (e.g. Karion Instant, Vivacel) showed marked deviations in behavior by particular parameters on the two machines. The results from both machines with respect to densification behavior complement one another.