Development and validation of a UPLC method for the quantification of related substances in chlordiazepoxide hydrochloride and clidinium bromide capsules

Objective: To investigate the degradation behavior of Clidinium Bromide, a key component of the Librax formulation, under various stress conditions and to develop a validated Ultra Performance Liquid Chromatography (UPLC) method for its simultaneous estimation with Chlordiazepoxide Hydrochloride. Methods: An innovative UPLC method was optimized to analyze both active pharmaceutical ingredients with high resolution and sensitivity. The mobile phase consisted of 40 mM phosphate buffer (pH 3.2) as Mobile Phase A and acetonitrile: methanol (70:30 v/v) as Mobile Phase B, delivered in gradient mode through an Acquity UPLC BEH C18 column (150 × 2.6 mm, 1.7 µm) at a flow rate of 0.3 mL/min. Stress conditions included acid, base, peroxide, humidity, thermal, aqueous, and UV exposure. Validation followed ICH guidelines for specificity, precision, and robustness. Results: The method demonstrated exceptional specificity in detecting Clidinium Bromide degradation products. Formation of related compound A and Benzilic acid was confirmed under particular conditions. All validation parameters met ICH requirements, underscoring the method’s reliability and reproducibility. Conclusion: This study offers a scientifically sound and validated UPLC approach for monitoring the stability of Clidinium Bromide in pharmaceutical formulations. The findings provide a robust analytical foundation for future formulation studies and quality control applications.