Estimation of Memantine Hydrochloride Using Ultraviolet-Visible Spectrophotometry in Bulk Drug and Formulation

Memantine HCl (ME-HCl) is a novel class of Alzheimer's disease medication acting on glutamatergic system by blocking NMDA glutamate receptors. ME-HCl is lacking of chromophores or auxochromes, thus it shows no distinct absorption in UV-VIS region. Therefore, no direct UV spectrophotometry method is available for its analysis. Thus, main aim of present study was to develop and validate simple and sensitive UV spectrophotometric method for estimation of ME-HCl and application of validated method for routine analysis of ME-HCl. Me-HCl was converted to free base with ammonia and allowed to react with iodine. The complex formed, shows UV absorptions bands at two wavelengths, 291 nm and 365 nm, but method was validated using 291 nm as λ_max. The Lambert-Beer's law is obeyed in range of (10-30 μg/ml). Developed method was found to be linear (r² = 0.9999), accurate (102.2 %), precise (% RSD<1 %) and sensitive (LOD = 2.51 μg/ml, LOQ = 7.62 μg/ml). The method was successfully applied to marketed formulation and % purity was found to be 97.17 % w/w.