LAUSR

BACKGROUND Careful review of the scientific databases revealed that no stability-indicating analytical method is available for the binary mixture of Allopurinol (ALO) and Thioctic Acid (THA). OBJECTIVE A comprehensive stability-indicating HPLC-DAD procedure has been executed for concurrent analysis of ALO and THA. METHODS Successful chromatographic separation of the cited drugs was reached using Durashell C18 column (4.6 × 250 mm, 5 µm particle size). The mobile phase was comprised of a mixture of acidified water (pH 4.0) using phosphoric acid and acetonitrile pumped in gradient elution mode. For quantification of ALO and THA, their respective peak areas were recorded at 249 nm and 210 nm. A systematic validation of analytical performance was investigated in terms of system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. RESULTS ALO and THA peaks emerged at retention times 4.26 and 8.15 min, respectively. Linear ranges for ALO and THA were 5-100 µg/mL and 10-400 µg/mL, respectively with correlation coefficient values exceeding 0.9999. Both drugs were exposed to conditions of neutral, acidic and alkaline hydrolysis, oxidation and thermal decomposition. Stability-indicating features have been demonstrated by resolution of the drugs from their forced degradation peaks. For verification of peak identity and purity, the diode-array-detector (DAD) was utilized. In addition, degradation pathways for the cited drugs were postulated. Besides, separation of both analytes from about 13 medicinal compounds of different therapeutic classes disclosed optimum specificity of the proposed method. CONCLUSION Advantageous application of the validated HPLC method for the concurrent analysis of ALO/THA in their tablet dosage form was accomplished. HIGHLIGHTS So far, the described HPLC-DAD method is considered the first detailed stability-indicating analytical study for this pharmaceutical mixture.