Stability Indicating Hptlc Method for the Simultaneous Determination of Amlodipine Besylate and Telmisartan from Tablet Dosage Form

Amlodipine besylate and Telmisartan are used in the treatment of hypertension. A simple, selective and stability indicating High-performance thin-layer chromatography method has been established for the simultaneous analysis of Amlodipine besylate and Telmisartan. The method uses aluminum-backed silica gel 60F₂₅₄ TLC plates as stationary phase with ethyl acetate: methanol: ammonia: glacial acetic acid [7.5:1.5:1.0:0.2 (v/v/v/v)] as mobile phase. Densitometric analysis was carried out in the absorbance mode at 226 nm. This system was found to give compact bands for Amlodipine besylate and Telmisartan with Rf values of 0.34±0.02 and 0.60±0.02 respectively. Linear relationships were obtained between response and amount of drug with high correlation coefficients (r²) in the range 500-6000 ng band^-1 for Amlodipine besylate (r²=0.9951) and 1000-8000 ng band^-1 for Telmisartan (r²= 0.9982). The method was validated for precision, accuracy and robustness as per ICH guidelines. Amlodipine besylate and Telmisartan were subjected to acid, base, oxidation, dry heat, wet heat and photo degradation studies. The degradation products obtained were well resolved from the pure drugs with significantly different Rf values. As the method could effectively separate the drugs from its degradation products, it can be used for stabilityindicating analysis.