A multicenter, randomized, open-label, prospective study to estimate the add-on effects of memantine as Ebixa oral pump on language in moderate to severe Alzheimer's disease patients already receiving donepezil

This study will evaluate the pharmacological efficacy on language capability and compliance with combination of new Ebixa oral pump and donepezil compared to donepezil only in patients with probable Alzheimer\'s disease. Primary objective is to evaluate the efficacy of memantine on language capability in moderate to severe Alzheimer\'s disease patients who are taking stable donepezil treatment.Secondary objectives are to evaluate the efficacy of maintain on cognitive function and disease progression with K-MMSE, NPI, ROSA, and SIB-short form in probable AD.