Integrating green analytical chemistry and analytical quality by design: an innovative approach for RP-UPLC method development of ensifentrine in bulk and inhalation formulations

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is a significant global health issue, worsened by pollution and modernisation. Ensifentrine (EFT), a new dual inhibitor of phosphodiesterase PDE3 and PDE4, is being developed for inhalation to target airway inflammation, bronchodilation, and ciliary function in COPD treatment. Objective: This study aims to develop and validate a new quantification method for Ensifentrine, as no previous techniques are available, by integrating analytical quality-by-design (AQbD) and green analytical chemistry (GAC) principles. Methods: An AQbD framework, utilizing Design-expert® software and a central composite design, optimized the RP-UPLC method. The optimized conditions involved isocratic separation on an ACQUITY UPLC HSS C18 SB column at ambient temperature, with a mobile phase of 0.01 N KH2PO4 (pH 5.4) and acetonitrile (66.4:33.6 v/v), a flow rate of 0.27 mL/min, and PDA detection at 272.0 nm. Results: The statistical analysis confirmed the model’s significance and normal distribution. The method, validated according to ICH guidelines, showed good linearity (r2 = 0.9997) over a range of 3.75–22.5 μg/mL, with an LOD of 3.3 μg/mL and LOQ of 10 μg/mL. It was successfully applied to bulk materials and pharmaceutical formulations with statistical comparisons. Green chemistry assessment: The greenness of the developed method was evaluated using tools such as ComplexMoGAPI, AGREE, BAGI, Green certificate-modified Eco-scale, and ChlorTox Scale. Additionally, the EVG method evaluation tool was also used to assess environmental impact, with the results shown in a radar chart. Conclusion: This study presents a sensitive and robust RP-UPLC method for quantifying Ensifentrine, combining AQbD and GAC principles. The method, validated according to ICH guidelines, also ensures environmental sustainability. This approach sets a precedent for future analytical method development in pharmaceutical sciences with a focus on sustainability.