Towards a better understanding of dry binder functionality.

It is of great importance to get a deeper understanding of the binding behaviour and functionality of different types of dry binders, since dry binders are crucial to ensure appropriate properties of dry granules and tablets. Based on previous studies, the most effective dry binders of chemically different types have been chosen to apply a new approach analysing the compressibility of tablets made from pure dry binders. Therefore, tablets were compressed at different tableting speeds to reveal binding behaviour of dry binders. Viscoelasticity, plasticity or abrasiveness were derived from force-displacement curves of tablets, which were manufactured at varying tableting pressure. In addition, elastic recovery, tabletability, fracture energy and out-of-die Heckel analysis were performed in order to get a comprehensive understanding on mechanical properties of dry binder for tableting. The new approach indicated explanations for results of previous studies in terms of tablet tensile strength, friability and dry granule properties. It enables a rational selection of dry binders for certain processes.

Impact of Different Dry and Wet Granulation Techniques on Granule and Tablet Properties: A Comparative Study.

Four granulation techniques were compared evaluating their impact on granule properties and the tablet tensile strength. A common formulation was chosen to be processed with both wet and dry granulation techniques: roll compaction/dry granulation, high-shear granulation, twin-screw granulation, and fluidized-bed granulation. The produced granules were characterized in terms of granule size distribution, X-ray powder diffraction, scanning electron microscopy, porosity, and strength. Granules were tableted, and the tablets were evaluated in terms of tensile strength and mass variation. A particular focus was given to granule strength measurements. Granule strength showed to be strongly affected by the used granulation technique. Moreover, a nonlinear inverse correlation was identified between granule strength and tablet tensile strength. High-shear granulation produced the densest and strongest granules, which presented the lowest tablet tensile strength. Granules manufactured by roll compaction/dry granulation showed no loss in tabletability with the used formulation even for the more compacted and strong granules. Tablets produced by the fluidized-bed granulation showed the best properties in terms of tensile strength and mass variation. However, twin-screw granulation presented comparable results for the specific formulation evaluated in the study, thus revealing a great potential of this technique.

Roll Compaction and Tableting of High Loaded Metformin Formulations Using Efficient Binders.

Metformin has a poor tabletability and flowability. Therefore, metformin is typically wet granulated with a binder before tableting. To save production costs, it would be desirable to implement a roll compaction/dry granulation (RCDG) process for metformin instead of using wet granulation. In order to implement RCDG, the efficiency of dry binders is crucial to ensure a high drug load and suitable properties of dry granules and tablets. This study evaluates dry granules manufactured by RCDG and subsequently tableting of high metformin content formulations (≥ 87.5%). Based on previous results, fine particle grades of hydroxypropylcellulose and copovidone in different fractions were compared as dry binders. The formulations are suitable for RCDG and tableting. Furthermore, results can be connected to in-die and out-of-die compressibility analysis. The addition of 7% of dry binder is a good compromise to generate sufficient mechanical properties on the one hand, but also to save resources and ensure a high metformin content on the other hand. Hydroxypropylcellulose was more efficient in terms of granule size, tensile strength and friability. Three percent croscarmellose was added to reach the specifications of the US Pharmacopeia regarding dissolution. The final formulation has a metformin content of 87.5%. A loss in tabletability does not occur for granules compressed at different specific compaction forces, which displays a robust tensile strength of tablets independent of the granulation process.