HPTLC validated stability indicating assay method for marketed herbal antihypertensive formulations
Background: Reserpine is an indole alkaloid and found to be very unstable in various conditions previously. Here a simple, selective, precise and stability indicating high-performance thin-layer chromatographic method of analysis of reserpine was developed and validated. Materials and methods: The method employed TLC plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consists of chloroform:acetone (7:3). This system was found to give well separated spots of reserpine at Rf (0.28 ± 0.02). The analysis of reserpine was carried out at 268 nm. Results: The linear regression analysis data for the calibration plots showed good linear relationship with r = 0.998 and 0.999 with respect to peak height and peak area, respectively, in the concentration range 200e1000 ng per spot. The method was validated for accuracy, precision, recovery and robustness. The limits of detection and quantification were 109.85 and 292.10 ng per spot, respectively. The conditions prescribed in the parent drug stability testing guidelines (Q1AR) issued by International Conference on Harmonization (ICH). Conclusion: The present study describes degradation of reserpine under different ICH prescribed stress conditions (acid and base hydrolysis, oxidation, dry and wet heat degradation and photo-degradation) and establishment of stability indicating HPTLC assay. The drug undergoes degradation under acidic and basic conditions, oxidation, dry and wet heat treatment and photo degraded. As the method could effectively separate the drug form its degradation products, it can be employed as a stability indicating one. Key words: Reserpine,Rauwolfia serpentina,HPTLC,Stability indicating,Stress degradation.