Development and Validation of TLC-Densitometry Method for Simultaneous Determination of Telmisartan and Amlodipine Besylate in Bulk and Tablets

A rapid, simple, and selective high performance thin layer chromatographic method was developed and validated for simultaneous estimation of telmisartan and amlodipine besylate in pharmaceutical dosage forms. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system comprised: tetrahydrofuran: dichloroethane: methanol: ammonia solution (6.0:2.0:1.0:0.4 v/v). This system was found to give compact spots for both telmisartan (Rf value of 0.22 ± 0.02) and amlodipine besylate (Rf value of 0.45 ± 0.02). Spectrodensitometric scanning-integration was performed at a wavelength of 326 nm. The polynomial regression data for the calibration plots showed good linear relationship with r2 = 0.9993 in the concentration range of 1,200–7,200 ng for telmisartan and 400–1,400 ng for amlodipine besylate with r2 = 0.9996. The method was validated for precision, accuracy, ruggedness, and recovery. The minimum detectable amounts were found to be 149.41 ng and 53.07 ng for telmisartan and amlodipine besylate, respectively. The limits of quantitation were found to be 452.78 ng for telmisartan and 160.83 ng for amlodipine besylate. Statistical analysis proves that the method is reproducible and selective for the simultaneous estimation of telmisartan and amlodipine besylate. Key words: Amlodipine besylate, HPTLC, simultaneous determination, telmisartan.