Analytical Method Development and Validation for Determination of Relugolix in Bulk Drug and Its Tablet Dosage Form Using HPLC Method

Abstract

The present research focuses on the development and validation of a precise, accurate, and
robust High-Performance Liquid Chromatography (HPLC) method for the quantitative estimation
of Relugolix, a potent gonadotropin-releasing hormone (GnRH) receptor antagonist, in both its bulk
drug and pharmaceutical tablet dosage form. Relugolix has recently gained prominence in the
treatment of hormone-sensitive conditions such as advanced prostate cancer and uterine fibroids,
necessitating a reliable analytical approach for routine quality assessment. The study aimed to establish
a chromatographic method that ensures optimum separation, sharp peak symmetry, and reproducible
retention time while maintaining simplicity and cost-effectiveness for laboratory applications. The
chromatographic separation was achieved using a C18 reverse-phase column under isocratic
conditions with a suitable mobile phase composition of acetonitrile and phosphate buffer in an
optimized ratio, maintaining a flow rate of approximately 1.0 mL/min. Detection was performed at a
wavelength specific to the λmax of Relugolix using a UV detector, ensuring adequate sensitivity and
selectivity. The method was systematically validated according to the International Council for
Harmonisation (ICH) Q2(R1) guidelines, assessing critical parameters such as linearity, accuracy,
precision, specificity, robustness, limit of detection (LOD), and limit of quantitation (LOQ).
Linearity was demonstrated within the selected concentration range, showing an excellent correlation
coefficient (r² > 0.999), confirming the proportionality between concentration and peak area. Recovery
studies at different levels established the accuracy of the method with recoveries within acceptable
limits (98–102%), while precision studies confirmed its reproducibility with low %RSD values. The
method exhibited significant sensitivity with low LOD and LOQ, enabling accurate detection even at
trace levels. Robustness testing under slight deliberate variations of chromatographic parameters
confirmed the stability and reliability of the analytical system. The developed HPLC method proved to
be simple, rapid, and highly efficient for routine analysis of Relugolix in both bulk and tablet dosage
forms. Its validation ensures suitability for use in quality control laboratories, pharmaceutical industries, and regulatory studies requiring accurate quantification of Relugolix. This analytical
approach thus provides a strong foundation for future formulation development and stability
assessment studies involving this therapeutic compound.