"Simultaneous quantification of nystatin, triamcinolone acetonide, neomycin sulfate and gramicidin D in transferosomal gel by rapid stability indicating HPLC method with PDA detector".

The present study aimed to develop and validate a simple, rapid and stability-indicating high-performance liquid chromatographic (HPLC) method for the simultaneous quantification of nystatin (Nys), neomycin sulfate (NS), triamcinolone acetonide (TAC) and gramicidin D (Gr) in bulk drug samples and transferosomal gel formulations. Chromatographic separation was achieved on an Agilent Eclipse C18 (250 × 4.6 mm, 5 μm) using a mobile consisting of methanol and 0.1% orthophosphoric acid (30:70, v/v). The flow rate was maintained at 1.0 mL/min, and detection was carried out at 260 nm using a Photo Diode Analyzer (PDA) detector. Under the optimized chromatographic conditions, all four analytes were eluted with symmetrical peaks, satisfactory resolution and acceptable theoretical plate counts within a run time of 12 min. The method exhibited excellent linearity over concentration ranges of 25-150 μg/mL for TAC, 62.5-375 μg/mL for Nys, 250-1,500 μg/mL for NS and 6.25-37.5 μg/mL for Gr, with correlation coefficients greater than 0.999 for all analytes. The developed method was validated according to International Council for Harmonization guidelines and demonstrated acceptable accuracy, with percentage recoveries ranging from 98 to 102% and precision, with percentage relative standard deviation values below 2%. Forced degradation studies were performed under acidic, alkaline, oxidative, reductive, thermal, photolytic, peroxide and hydrolytic conditions. The analytes exhibited degradation ranging from ~11 to 12.1%, confirming the stability-indicating capability of the method. The proposed method is simple, accurate, precise, robust and suitable for the routine quantification of Nys, NS, TAC and Gr in bulk drug substances, transferosomal gel formulations and marketed pharmaceutical products.