Quantification of febuxostat polymorphs using powder X-ray diffraction technique

Febuxostat is a pharmaceutical compound with more than 20 polymorphs of which form A is most widely used and usually exists in a mixed polymorphic form with form G. In the present study, a quantification method for polymorphic form A and form G of febuxostat (FEB) has been developed using powder X-ray diffraction (PXRD). Prior to development of a quantification method, pure polymorphic form A and form G are characterized. A continuous scan with a scan rate of 3 degrees min(-1) over an angular range of 3-40 degrees 2 theta is applied for the construction of the calibration curve using the characteristic peaks of form A at 12.78 degrees 2 theta (I/I-0 100%) and form G at 11.72 degrees 2 theta (I/I-0 100%). The linear regression analysis data for the calibration plots shows good linear relationship with R-2 = 0.9985 with respect to peak area in the concentration range 10-60 wt.%. The method is validated for precision, recovery and ruggedness. The limits of detection and quantitation are 1.5% and 4.6%, respectively. The obtained results prove that the method is repeatable, sensitive and accurate. The proposed developed PXRD method can be applied for the quantitative analysis of mixtures of febuxostat polymorphs (forms A and G). (C) 2015 Elsevier B.V. All rights reserved.