Chalapathi institute of pharmaceutical sciences,
guntur, a.p, india.
Amlodipine (as besylate, mesylate or maleate) is a long-acting calcium channel blocker (dihydropyridine (DHP) class) used as an anti-hypertensive and in the treatment of angina. Indapamide is a thiazide diuretic used in the treatment of hypertension, as well as decompensated cardiac failure. Six new, simple, accurate and precise methods have been developed and validated according to ICH guidelines for the simultaneous estimation of Amlodipine and Indapamide in their combined dosage form (four UV-Spectrophotometric, one colorimetric and one RP-HPLC methods).
First method is based on simultaneous estimation using two wavelengths, 365 nm (λmaxof AMLO) and 279 nm (λmaxof INDA) by simultaneous equation method. The second method involves the use of first order derivative technique, here 293 nm, the zero crossing point of AMLO, 279 nm, the zero crossing point of INDA were used for the estimation. The third method is based on Q-absorption Ratio method using two wavelengths 365 nm (λmaxof AMLO) and 312 nm (Isoabsorptive point). In the dual wavelength method two wave lengths 270 nm and 288 nm were selected as λ1 and λ2 for the estimation of AMLO, INDA shows the same absorbance at these wavelengths. Similarly, wavelengths 350 nm and 378 nm were selected as λ1 and λ2 for the estimation of INDA, AMLO shows the same absorbance at these wavelengths.Colorimetry: The method is based on use of MBTH reagent for simultaneous estimation of AMLO and INDA using two wavelengths, 626 nm (λmaxof AMLO) and 600 nm (λmaxof INDA).