Drug-excipient interactions amorphous product

XRD is an excellent technique to study drug-excipient interactions, provided the drug and the excipients are crystalline. In a solid mixture, the powder pattern of each crystalline phase is produced independently of the other constituents. Thus the diffraction pattern of a powder mixture will be the summation of the diffraction patterns of the individual constituents. If the drug-excipient interaction results in a crystalline product, this will be characterized by the appearance of new peaks in the powder pattern. However, if the interaction results in an amorphous product, this will become evident from the broad halos in the pattern. 

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