The compressibility of pharmaceutical materials is a critical quality attribute of a tablet that determines the force needed to make the tablet. This in turn affects all tablet properties such as disintegration, dissolution and adsorption of the drug as well as physical properties such as hardness and friability. Many of the problems associated with tablet quality relate to the fact that the effect of material compressibility on tablet properties are not measured during development even though it is known to have considerable effect on drug dissolution and absorption as well as tablet hardness and friability.