A QbD-guided, eco-friendly UHPLC method for simultaneous estimation of tezacaftor and ivacaftor: a stability-indicating and green analytical approach

Abstract This study reports the development and validation of a novel ultra-high-performance liquid chromatography (UHPLC) method that is both stability indicating and environmentally sustainable, intended for the simultaneous quantification of tezacaftor (TZF) and ivacaftor (IVF) in pharmaceutical formulations. Using analytical quality-by-design (AQbD) principles, critical method parameters (CMPs), including flow rate and column temperature, were optimized using central composite design (CCD). Separation was achieved on an ACE Excel Super C18 column (100 × 2.1 mm, 2 µm) using an isocratic mobile phase of acetonitrile and water at 75 : 25 v/v, 0.3 ml min−1 , with detection at 254 nm. Validation according to the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2(R1) demonstrated excellent linearity (R² > 0.999), accuracy (98–102% recovery), precision (% relative standard deviation (% r.s.d.) < 2%) and sensitivity with limits of detection (LOD) and quantification (LOQ) 0.5/1.5 µg ml−1 (TZF) and 0.3/1.0 µg ml−1 (IVF). The stability-indicating nature of the method was confirmed through forced-degradation studies under various stress conditions, with peak purity analysis supporting its specificity. Sustainability assessment using the Analytical Eco-Scale (score: 80), GAPI and AGREE tools verified the method’s eco-friendly profile.