Solid state transformations in consequence of electrospraying – A novel polymorphic form of piroxicam

• Electrospraying was used for drug particle production.
• In the studies, the electrosprayed piroxicam exhibited an unknown crystal structure.
• The structure was concluded to represent a novel polymorphic form of piroxicam.
• Electrospraying can offer a new method for drug polymorph screening.

The aim of the research was to verify that electrospraying of piroxicam yielded a new polymorphic form of this drug. In the experiments, piroxicam was dissolved in chloroform and the solution was atomised electrostatically. Subsequently, the charged droplets were neutralised and dried. The solid drug particles were collected and analysed by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, high performance liquid chromatography, and infrared and Raman spectroscopy. The X-ray diffractogram measured for the electrosprayed piroxicam particles did not match with any of the known piroxicam crystal structures (Cambridge Crystallographic Data Centre). The variable temperature X-ray diffraction showed that the structure recrystallised completely into piroxicam polymorphic form I during heating. No degradation products or solvate removal was detected by high performance liquid chromatography and thermal analysis. The infrared and Raman spectra of the electrosprayed piroxicam were compared to those of form I, and some notable differences in the peak positions, shapes and intensities were detected. The results indicate that electrospraying leads to piroxicam crystallisation in a currently unknown polymorphic form.

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