Development of Evaluation and Validation Technique for Assessment of Stability Content of Melatonin and Pyridoxine Hydrochloride Tablets using RP-HPLC

Abstract

Melatonin and Pyridoxine Hydrochloride combination drugs are used in the treatment of insomnia. Despite their widespread usage, the simultaneous assessment of these substances in tablet form, lack stability-indicating techniques. To warrant stability of the tablet under varied storage conditions, the study aims to establish a novel RP-HPLC technique for the estimation of Melatonin and Pyridoxine simultaneously in the formulation. Additionally, content uniformity in the tablet is also essential to ensure that patients receive a reliable and efficient dose. Hence, the formulation was also evaluated for content uniformity. Waters symmetric C18 column (3.9 x 150 mm, 5 µm) was used to obtain sufficient chromatographic separation with well-defined peaks. The method used flow rate of 1-mL/min, column oven temperature of 25°C, injection volume 10 µL and Diode array detector at 280 nm. Mobile phase contains 20% methanol and 80% buffer (mix 670 mL water, 320 mL methanol, 10 mL glacial acetic acid and 1.4 g of 1-hexane sulphonic acid sodium salt). Method validation comprised tests for accuracy, precision, robustness, specificity, linearity and stability.  Method was linear (r > 0.999), accurate (recovery: 98% to 102%), and precise (%RSD < 2%). Analyte stability was observed for upto 6 months in accelerated stability conditions, intermediate stability conditions and long-term stability conditions. Content uniformity tests showed that drug contents are within acceptable range.