Validated Stability-indicating NP-HPTLC/Densitometry Method for the Assay of Zolpidem Tartrate in Pharmaceutical Dosage Form

Background: A simple, precise stability-indicating NormalPhase Thin-Layer Chromatography (NPTLC)/ Densitometry method has been studied for estimation of zolpidem tartrate in bulk and in tablet formulation. Method: The chromatographic separation was accomplished on aluminium backed precoated silica gel 60 F254S as the stationary phase using Ethyl acetate: Methanol: triethylamine (9: 1: 0.3 v/v) as mobile phase. Densitometric analysis of zolpidem tartrate was achieved at λ max 293 nm. The method was validated for robustness, precision and accuracy. Stress degradation of zolpidem tartrate was carried out under various reaction conditions including acid, base, oxidation, photo-degradation and dry heating treatment. Result: This system was found to give compact spot for zolpidem tartrate at Rf value 0.56 ± 0.02. The data of linear regression analysis of zolpidem tartrate indicated a good linear relationship over the range of 300 – 1800. LOD and LOQ found 18.10 and 54.84 ng. Resulted stress drugs were analyzed with the developed TLC/ densitometry method. Conclusion: Statistical analysis proves that the method is repeatable and selective for the estimation of zolpidem tartrate in bulk and in formulation. As the method could effectively separate the drug from its degradation products, it can be employed as a stabilityindicating method.