Crystallization and disorder of the polytypic α₁ and α₂ polymorphs of piroxicam

Abstract

The polytypic α1 and α2 polymorphs of piroxicam are described and it is shown that they can be crystallized controllably.

Crystal Growth in Gels from the Mechanisms of Crystal Growth to Control of Polymorphism: New Trends on Theoretical and Experimental Aspects

“…A more concise way of using this term could probably emerge from the effects of polymorphism itself. At a pharmaceutical level, the presence of polymorphs of a compound causes differences in solubility and stability, and in the formulation procedures for that particular compound [2][3][4][5][6][7][8][9][10][11]. In biomineral systems, organisms use different polymorphs according to the system and function that are needed [12][13][14].…”

Periodic DFT Calculations—Review of Applications in the Pharmaceutical Sciences

“…Already, a term, "NMR crystallography", has been created [197][198][199] to describe an approach which combines performing experimental NMR and generating spectra with a DFT-based software in order to confirm or create the crystal structure of the studied system. It has been already proven that a research constructed in this way delivers more accurate data, compared to the separate application of these two techniques [200][201][202]. In some cases it is plainly stated that the proper designation of the hydrogen positions would not be possible at all, unless the combination of DFT and ssNMR had been used [203].…”

Structure–property correlations in piracetam polytypes

“…For example, we have studied several pharmaceutically-relevant polytypic systems, in which consistent two-dimensional layers of molecules are arranged in different ways, including aspirin, 6 felodipine 7 and piroxicam. 8 We have observed twinning and "intergrowth polymorphism" in these systems, which can lead to variations in the physical properties of crystals on account of differing microstructures.…”