Stability Indicating UHPLC-PDA Assay for Simultaneous Determination of Antazoline Hydrochloride and Naphazoline Hydrochloride in Ophthalmic Formulations.

In the present study, a newly developed method based on ultrahigh performance liquid chromatography (UHPLC) was optimized for the simultaneous determination of antazoline hydrochloride (ANZ) and naphazoline hydrochloride (NFZ) in ophthalmic formulations. Isocratic separation of ANZ and NFZ was performed at 40 °C with an ACE Excel 2 C18-PFP column (2 μm, 2.1 × 100 mm) at a flow rate of 0.6 mL min-1 whereas the mobile phase consisted of acetonitrile/phosphate buffer (60:40, v/v, pH 3.0) containing 0.5% triethylamine. Both analytes were detected at a wavelength of 285 nm and the injection volume was 1.0 μL. The overall run time per sample was 4.5 min with retention time of 0.92 and 1.86 min for NFZ and ANZ, respectively. The calibration curve was linear from 0.500-100 μg mL-1 for ANZ and NFZ with a correlation coefficient ≥ 0.9981 while repeatability and reproducibility (expressed as relative standard deviation) were lower than 1.28 and 2.14%, respectively. In comparison with high-performance liquid chromatography (HPLC), the developed UHPLC method had remarkable advantages over HPLC as the run time was significantly reduced by 3.4-fold with a 5-fold decreased solvent consumption. Forced degradation studies indicated a complete separation of the analytes in the presence of their degradation products providing high degree of method specificity. The proposed UHPLC method was demonstrated to be simple and rapid for the determination of ANZ and NFZ in commercially available ophthalmic formulations providing recoveries between 99.6 and 100.4%.