Performance Characteristics of a Novel Vibration Technique for the Densification of a Powder Bed within a Die of a Rotary Tablet Press - a Proof of Concept

A novel approach to avoid capping and/or lamination by application of external lower punch vibration

Capping as well as lamination are two common problems, which affect the resulting product quality of the tablet. Usually, capping and lamination occur during or after tablet manufacturing, and may therefore influence follow-up processes such as the coating. In this context, there is an urgent need for approaches to overcome the occurrences of capping and lamination. In the present study, a novel lower punch vibration technique was used to decrease the capping or lamination tendency of different powder formulations. Different microcrystalline cellulose types, as well as an API (acetaminophen), were selected as model powders. The powders were investigated regarding their powder flow, density, particle morphology, and surface area. Moreover, the manufactured tablets were characterized regarding their tablet weight, tensile strength, and capping or lamination indices. It was shown that the capping or lamination tendency was strongly affected by the physical powder properties, the formulation composition, and the adjusted turret speed. In addition, the application of externally applied lower punch vibration led to a pronounced decrease of the capping or lamination tendency and improved mechanical stability of the manufactured tablets.

Application of Externally Applied Lower Punch Vibration and its Effects on Tablet Manufacturing

PURPOSE

In the present study the influence and application of a newly developed external lower punch vibration system for an improved die filling on a running rotary tablet press was investigated.

METHODS

Tablets were manufactured at different conditions (with and without vibration) and characterized regarding their direct compressibility and mechanical stability. Thus, two typical pharmaceutical binders for direct compression (Parmcel 102 and Tablettose® 80) were compared with two binders unsuitable for direct compression (Ceolus® KG1000 and GranuLac® 200). The powders were characterized by helium pycnometry, laser diffraction, scanning electron microscopy, and by determination of the powder flow. Furthermore, a novel technique to determine the occurrences of segregation within a tablet after manufacturing was introduced. For this purpose, a powder blend containing one spray-colored type of microcrystalline cellulose (Vivapur® 200) were prepared.

RESULTS

It was shown that under application of externally applied lower punch vibration, the powder flow into the die increased and thus the die filling process was significantly improved. Hence, it was possible to manufacture tablets from powders, which are actually unsuitable for direct compression. In addition, the mechanical stability of the produced tablets was distinctly improved by application of lower punch vibration, whereby the occurrence of segregation was comparatively low.

CONCLUSION

In summary, lower punch vibration allows a more efficient die filling, whereby the powder flow as well as mechanical stability of the tablets are improved.