Implementation of analytical quality by design and green chemistry principles to develop an ultra-high performance liquid chromatography method for the determination of Fluocinolone Acetonide impurities from its drug substance and topical oil formulations

Abstract

An anti-inflammatory skin condition is treated with fluocinolone acetonide (FLA), a synthetic corticoid. The current study aims to develop a stability-indicating UPLC method for the determination of impurities present in fluocinolone acetonide and its topical oil formulation. The method development was performed by implementing Analytical Quality by Design (AQbD) and green chemistry principles. A detailed risk assessment was conducted based on the cause-and-effect relationship. d-optimal split-plot design was employed to screen the critical method parameters (CMPs). The central composite design (CCD) was employed to optimize the final method conditions. p-values for the model and lack of fit were <0.0001 and >0.05, respectively, which indicates the best fit statistical model for the studied responses (peak resolutions R1 - R5). The critical method attributes (CMAs) and CMPs such as the ratio of ACN: Water in mobile phase-B as 600:400 (v/v), the ratio of mobile phase-A & B in initial gradient program as 60:40, flow rate as 0.3 mL min^-1, and column oven temperature as 50 °C were optimized from the CCD. The best possible separation among all components was achieved with a gradient elution using Waters Acquity UPLC HSS C₁₈, 100 mm × 2.1 mm, 1.8 µm analytical column. The optimized gradient program is time (min)/%B: 0.0/40, 1.5/40, 6.0/60, 8.0/70, 9.0/80, 12.0/100, 15.0/100, 15.1/40 & 18.0/40. Optimization of diluent is highly critical for any oil-based formulations. The experimental results show that acetonitrile is the most suitable diluent for the current study. The method validation was executed in compliance with ICH and USP 〈1225〉 guidelines. Mean recovery of the impurities ranged between 95.7 and 105.7%, the correlation coefficient(r) was> 0.999, the RSD values (n = 6) ranged between 0.9 - 3.2% across the range for LOQ - 150% levels. The peaks from the specificity study did not interfere with the known and active analyte peaks. The major degradation products were identified as Imp-C, B, and A, and established their degradation pathways from FLA based on the stress studies. The method greenness was evaluated using GAPI, AGREE and analytical eco scale and found that the method is green.

Keywords: Analytical quality by design; Central composite design; Fluocinolone acetonide; Green chemistry; Topical oil formulation.