Derivatization‐Based Densitometric Approach Along With Greenness Assessment for Simultaneous Evaluation of Duloxetine Hydrochloride and Pregabalin: An Application to Pharmaceutical Analysis

The fixed-dose combination of pregabalin and duloxetine hydrochloride is mainly used in the treatment of neuropathic pain. Sensitive determination of drugs like pregabalin is challenging by chromatographic methods using UV detection due to their nonchromophoric nature. This study presents the development of a validated high-performance thin-layer chromatography (HPTLC) method for the simultaneous determination pregabalin and duloxetine hydrochloride in formulation. Because pregabalin has a weak chromophoric system, it was visualized using a derivatization reagent containing ninhydrin. Optimum separation of pregabalin and duloxetine hydrochloride was achieved on silica gel 60 F₂₅₄ plates using methanol:dichloromethane:acetone:ammonia (8:1:1:0.2, v/v/v/v). Good resolution was achieved with R_f values of 0.34 ± 0.02 and 0.52 ± 0.02 for duloxetine hydrochloride and pregabalin, respectively. The method was validated as per the ICH Q2(R1) guidelines. Linearity range was found between 200 and 450 ng/band for duloxetine and 500 and 1125 ng/band for pregabalin. Low %RSD values shows that the developed method is precise. Greenness assessment of the developed method was evaluated using three different assessment tools, namely, Analytical Eco-Scale, GAPI, and AGREE This is the first validated derivatization-based HPTLC method for simultaneous analysis of duloxetine hydrochloride and pregabalin.