A Validated Stability-Indicating LC Method for Fluocinonide in the Presence of Degradation Products, Its Process-Related Impurities and Identification of Degradation Products

Abstract

The objective of the current study was to develop a validated, specific and stability-indicating reverse phase liquid chromatographic method for the quantitative determination of fluocinonide and its related substances. The determination was done for active pharmaceutical ingredient and its pharmaceutical dosage forms in the presence of degradation products, and its process-related impurities. The drug was subjected to stress conditions of hydrolysis (acid and base), oxidation, photolysis and thermal degradation per International Conference on Harmonization (ICH) prescribed stress conditions to show the stability-indicating power of the method. Significant degradation was observed during acid, base hydrolysis, and peroxide degradation. The major degradants were identified by LC-MS, FTIR and 1 H/ 13 C NMR spectral analysis. The chromatographic conditions were optimized using an impurity-spiked solution and the samples generated from forced degradation studies. In the developed HPLC method, the resolution between fluocinonide and its process-related impurities, (namely imp-1, imp-2, imp-3, imp-4, imp-5, imp-6, imp-7 and imp-8) and its degradation products was found to be greater than 2.0. The chromatographic separation was achieved on a C18, 250 mm × 4.6 mm, 5 µm column. The LC method employed a linear gradient elution and the detection wavelength was set at 240 nm. The stress samples were assayed against a qualified reference standard and the mass balance was found to be close to 99.3%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.