Validated RP-HPLC-UV Method for Simultaneous Quantification of Aminophenazone, Dipyrine, and Chlorpheniramine Maleate in Pharmaceutical Formulations Considering Dipyrine Decomposition.

Aminophenazone, dipyrine, and chlorpheniramine maleate combined drug is used as antipyrine and analgesic. In this study, a rapid, robust, and straightforward high-performance liquid chromatographic (HPLC) technique was developed, optimized, and validated for simultaneous analysis of aminophenazone, dipyrine, and chlorpheniramine maleate taking into account decomposition of dipyrine. On a C18 (4.6 mm × 15 cm; 5 μm) Shim-pack column, aminophenazone, dipyrine, and chlorpheniramine maleate were successfully eluted by using mobile phase, comprising water: methanol: triethylamine: glacial acetic acid (70:28:1:1 v/v/v/v) at flow rate 1.0 mL/min and wavelength of 254 nm. About 5 mg/mL sodium sulfite in diluent and mobile phase was used to prevent the hydrolysis of dipyrine after several investigations. The validation parameters, including specificity, linearity, LOD/LOQ, precision, accuracy, robustness, and solution stability, were verified for performance of the method. In specificity study, there was not any interference with main peak. The constructed calibration curve was found to be linear in the concentration ranges of 0.1-1.0 (aminophenazone), 0.1-1.0 (dipyrine), 0.002-0.020 (chlorpheniramine maleate) mg/mL, respectively. The % recovery at different concentrations was within the (98.0-102.0) %. When the column temperature, the flow rate, wavelength, and mobile phase composition were changed, the absolute difference of the content at different modified conditions were within 2.0 (%RSD) of the original condition. The solution was stable upto 24 h in room temperature (benchtop), autosampler (15°C-25°C), and refrigerator (2-8 degree). This method was successfully employed for the analysis of aminopyrine, metamizole, and chlorpheniramine maleate in marketed products, and the results were satisfactory. The confirmed RP-HPLC-UV method may be a workable analytical approach on a routine analysis.