Integrating green analytical chemistry and analytical quality by design: an innovative approach for RP-UPLC method...

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.

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.

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.

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.

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.

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.