A stability-indicating RP-HPLC method for simultaneous estimation of sulopenem etzadroxil and probenecid in bulk drug and combined tablet dosage form

An economical, sensitive, robust, and stability-indicating RP-HPLC method was developed for the simultaneous estimation of Sulopenem Etzadroxil and Probenecid in binary mixture and combined tablet dosage forms. Chromatographic separation was attained using a SunFire C18 column (250 × 4.6 mm, 5 μm) with a mobile phase of acetonitrile and 0.1% formic acid (70:30 v/v) in an isocratic elution at a flow rate of 1.1 mL/min, and detection at 228 nm. The retention times of Sulopenem Etzadroxil and Probenecid were observed at 2.285 min and 3.046 min, respectively, with good resolution of 5.2 and tailing of 1 for both drugs. The validation of the method was conducted in accordance with ICH Q2(R1) guidelines. The results of accuracy (99.07–100.74%), precision (RSD < 2%), linearity (25–150 µg/mL; R² = 0.9996), specificity, and robustness met the acceptance criteria. The detection and quantification limits of Sulopenem Etzadroxil and Probenecid were calculated to be 0.42 µg/mL, 1.26 µg/mL, and 0.44 µg/mL, 1.33 µg/mL, respectively. The stability-indicating character of the method was demonstrated through various forced degradation studies, where the produced degradants were distinctly separated from the peaks of Sulopenem Etzadroxil and Probenecid with good resolution, and the peak purity angle values were less than the purity threshold values, confirming the peak purity. The assay of a marketed formulation showed 99.64% and 99.93% of the labeled claim for Sulopenem Etzadroxil and Probenecid, respectively. The simple mobile phase and short run time made the method suitable for regular quality control and stability testing of Sulopenem Etzadroxil, and Probenecid in pharmaceutical industries.