Amorphous pharmaceutical materials degree

Another physical property that can affect the appearance, bioavailability, and chemical stability of pharmaceuticals is degree of crystallinity. Amorphous materials tend to be more hygroscopic than their crystalline counterparts. Also, there is a substantial body of evidence that indicates that the amorphous forms of drugs are less stable than their crystalline counterparts [62]. It has been reported, for example,... 

There is actually no sharp distinction between the crystalline and amorphous states. Each sample of a pharmaceutical solid or other organic material exhibits an X-ray diffraction pattern of a certain sharpness or diffuseness corresponding to a certain mosaic spread, a certain content of crystal defects, and a certain degree of crystallinity. When comparing the X-ray diffuseness or mosaic spread of finely divided (powdered) solids, the particle size should exceed 1 um or should be held constant. The reason is that the X-ray diffuseness increases with decreasing particle size below about 0.1 J,m until the limit of molecular dimension is reached at 1-0.1 nm (10-1 A), when the concept of the crystal with regular repetition of the unit cell ceases to be appropriate. 

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