X-ray Diffraction Analysis of Linezolid Crystalline Forms as Part of Quality Control

Abstract

This work is a continuation of research on the use of X-ray diffraction analysis (XRD) for identification of medicines that exhibit polymorphism.The aim of the paper was to perform comparative XRD analysis of linezolid samples produced by different manufacturers.Materials and methods: the measurements were performed using an Empyrean X-ray powder diffraction system (PANalytical, Netherlands) with an X’Celerator linear solid-state detector using Ni-filtered CuKa radiation. The results were recorded at 1.5406 and 1.5444 А with the intensity ratio in the doublet of 2:1. The two-phase Rietveld refinement of the obtained diffractograms was used for the quantitative analysis.Results: the authors compared diffractograms of three commercial samples of linezolid. The revealed differences were analysed taking into consideration available literature on the polymorphic forms of linezolid. It was demonstrated that only forms II and IV should be considered as different polymorphs of linezolid.Conclusions: the study demonstrated that linezolid samples produced by different manufacturers could represent different polymorphs or mixtures thereof. The evaluation of linezolid quality by X-ray diffraction analysis requires the comparison of the obtained results with the diffractogram of the form IV reference standard. Relevant information should be provided by manufacturers in the product specification file.

Keywords

• quality control
• polymorphism
• linezolid
• x-ray diffraction analysis
• conformers