Greenness analysis of stability indicating RP-HPLC analytical method development and validation for simultaneous estimation of pregabalin and etoricoxib in pharmaceutical dosage form

Pregabalin (PRG) and etoricoxib (ETO) are co‑formulated for neuropathic pain therapy owing to complementary mechanisms. To develop and validate a green, stability‑indicating RP‑HPLC method for simultaneous quantification of PRG and ETO in tablets. Analysis was performed on a C18 column (250 × 4.6 mm, 5 μm) using methanol–phosphate buffer (pH 7, 60:40 v/v) at 1.0 mL/min flow rate with UV detection at 210 nm. The method was validated per ICH Q2(R2). Forced degradation (acid, base, oxidative, neutral, thermal, photolytic) was performed. Environmental impact was assessed via AGREE, AGREEprep, ComplexGAPI, and BAGI. Retention times: PRG at 3.02 min, ETO at 4.87 min (resolution = 4.32). Linearity was observed in 25–200 µg/mL (R² > 0.995). LOD/LOQ: PRG = 0.13/0.39 µg/mL; ETO = 0.47/1.42 µg/mL. Recoveries ranged from 99.0 to 99.31% (PRG) and 98.0–99.5% (ETO). Intraday/interday RSD < 1.7%. The method effectively separated analytes from degradation products. Greenness scores: AGREE = 0.78, BAGI = 80, AGREEprep = 0.62, ComplexGAPI showed moderate greenness. The method is rapid (< 5 min), accurate, precise, stability‑indicating, and eco‑friendly—suitable for routine quality control of PRG–ETO formulations.