It is generally said that, even with identical substances, solubility changes if the crystal form differs. Differences in crystal polymorphs sometimes cause the melt-in-the-mouth sensation of food to change, and, in the pharmaceutical field, changes in solubility within the body might result in differences in drug efficacy.

The physical properties of bulk pharmaceuticals vary according to differences in the crystal form, and affect factors such as stability, solubility and ingestion efficiency within the body.
DSC (Differential Scanning Calorimeter) and diffraction X-rays are typical methods used for evaluating the crystal form, and are chiefly used for evaluating the crystal form of individual bulk pharmaceuticals or for evaluation in batch processes. Raman spectrophotometry, however, enables in-situ measurement when crystallizing bulk pharmaceuticals from solutions and non-destructive inspection of solid preparations.