Abstract:

A stability-indicating high-performance liquid chromatography (HPLC) method has been developed and validated for the separation and determination of Retigabine and its related substances. The chromatographic separation was achieved on Agilent Eclipse Plus C₁₈ column (4.6 mm×150 mm, 5 µm). The mobile phase was constituted of triethylamine-phosphate buffer as A and acetonitrile as B. The analysates were then eluted under the gradient conditions as description in this paper. The forced degradation study validated that the newly developed method was specific and selective to the degraded products. The performance of the method was verified according to the present International Conference on Harmonisation (ICH) guidelines for specificity, linearity, accuracy, precision and robustness. The correlation coefficients for Retigabine and its six impurities were greater than 0.999, which was shown in the regression analysis. Limits of detection (LOD) of these impurities were in the range of 0.0092%–0.0103%, indicating the high sensitivity of the newly developed method. Accuracy of the method was determined on the basis of recoveries to be between 96.49% and 118.35% for all impurities. Relative standard derivation (RSD) receiving in the repeatabilityand intermediate precision experiment, was less than 1.0%. The method can be successfully applied to routine quantify and stability testing Retigabine and its related substances in bulk drugs.

Key words: Retigabine, HPLC, Related substances, Forced degradation