Eco-Friendly Non-Derivatized HPLC Approach for Simultaneous Determination of Pregabalin, Milnacipran, and Duloxetine Employed in Fibromyalgia Treatment

A novel, eco-friendly high performance liquid chromatography (HPLC) method was developed for the simultaneous determination of pregabalin (PRE), milnacipran hydrochloride (MIL), and duloxetine hydrochloride (DLU), FDA-approved fibromyalgia drugs. This method addresses challenges posed by their structural diversity and PRE's poor UV absorbance. By eliminating derivatization, it avoids hazardous reagents and reduces waste. Separation was achieved on a C18 column using a mobile phase of 45% 0.03M sodium dihydrogen phosphate buffer (pH 3.5), 30% acetonitrile, and 25% methanol at flow rate 0.9 ml/min, with UV detection at 210 nm. The column temperature was 30°C, and the injection volume was 20 µl. Linearity ranges were extended to 100–1600 µg/ml for PRE, 2–40 µg/ml for MIL and DLU, allowing direct dosage form analysis for combined formulations without PRE derivatization, with quantification limits of 91.200, 1.326, and 1.872 µg/ml, respectively. Validated per ICH guidelines and applied to pure drugs and formulations. Greenness assessments using analytical greenness metrics (AGREE) and complementary green analytical procedure index (Complex GAPI) confirmed its sustainability.