Identification and quantitative determination of eletriptan hydrobromide polymorphs: Thermal, diffractometric and spectrometric studies

The quantitative characterisation of the solid form of drug substances and drug products is gaining importance due to product quality and performance that is based on stringent regulatory guidelines. Therefore, in this study, thermal, X-ray diffraction and spectroscopic methods were evaluated to obtain a simple, quick and precise method for the quantitative analysis of binary mixtures of eletriptan hydrobromide polymorphs in powder form. The two polymorphs are discernible using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Quantitative methods using each technique were developed and validated using spiked standards prepared by geometrical mixing of the pure polymorphs. The estimated limit of detection values of the methods using DSC, PXRD and DRIFTS were determined to be 0.24%, 2.01% and 2.06%, respectively. A careful evaluation of the validation results from the three methods indicated that DSC performed better than PXRD and DRIFTS. The DSC method was determined to be the best alternative to PXRD and DRIFTS due to its measurement capability, simplicity, cost effectiveness and quickness. The real-time sample batch analysis was performed, and the advantages and applications of the study are discussed.