Evaluation of the effects of tableting speed on the relationships between compaction pressure, tablet tensile strength, and tablet solid fraction

It is well known that compression speed can have significant effects on the compaction properties of pharmaceutical powders. This is a challenge during scale up and technology transfer when tableting speeds are significantly increased. This study examined the effects of tableting speed on the compressibility (solid fraction vs. compaction pressure), tabletability (tensile strength vs. compaction pressure), and compactibility (tensile strength vs. solid fraction) of four common direct compression excipients and a placebo formulation. The tabletability and compressibility of some of these materials were observed to be speed dependent whereas the compactibility of all materials tested was essentially independent of tableting speed. It is therefore proposed that the compactibility profile (tensile strength vs. solid fraction) is a predictor that is independent of tableting speed and can be used to predict tablet strength during formulation development and scale up.