Development and Validation of an RP-UPLC Method for the Determination of Memantine and Donepezil in Capsule Dosage Form, Including a Comprehensive Stability Study.

RP-UPLC developed a simple, accurate and precise method for the simultaneous estimation of memantine and donepezil in capsule. The chromatogram was run through an ACQUITY UPLC CSH C18 column, 1.7 µm, 2.1 mm x 50 mm. A mobile phase containing 0.01 N KH 2 Po 4 buffer and 60:40 methanol was pumped through the column at a flow rate of 0.4 ml/min. The temperature was maintained at 38.0 °C. The optimized wavelength for memantine and donepezil was 250 nm. The retention times of memantine and donepezil were 0.572 minutes and 1.367 minutes, respectively. The percent RSD for memantine and donepezil were 0.4 and 0.6, respectively. The recovery rate was 100.43% and 99.95% for memantine and donepezil. The LOD and LOQ values obtained from the regression equations for memantine and donepezil were 0.13 ppm, 0.41 ppm and 0.09 ppm, 0.26 ppm, respectively. The regression equation for memantine is y = 8913.2x + 10674 and for donepezil y = 8018.2x + 4057.2. The storage times are shortened and the working time is shortened.