BPDO-1603 Intervention Trial in Patients With Moderate-to-severe Alzheimer's Disease

Inclusion Criteria: * A voluntary, written informed consent from the patient or the patient´s representative. * Male or female patients ≥ 45 years of age as of the date of informed consent. * Diagnosed with probable AD according to the National Institute on Aging-Alzheimer's Association \[NIA-AA (2011)\] criteria. * MMSE score of ≥ 5 and ≤ 20 during screening period. * CDR-GS of 2 \~ 3 or GDS of 4 \~ 7 during screening period. * Ongoing cholinesterase inhibitor therapy with stable dose of 10 mg/day donepezil hydrochloride for more than 12 weeks (inclusive) prior to screening, and can continue this therapy until randomization without any change in the dosage regimen of donepezil hydrochloride. Exclusion Criteria: * Magnetic resonance imaging (MRI) or computed tomography (CT) findings obtained within the past 12 months (ie, 48 weeks) from screening or at screening, as a cause of dementia other than probable AD. * History of other organic disease, such as vascular dementia, CNS infections (e.g., human immunodeficiency virus \[HIV\], syphilis), head injury, Creutzfeldt-Jakob disease, Niemann-Pick's disease, Huntington's disease, Parkinson's disease, epilepsy, or stroke. * Evidence of other neurological disorders which include seizure disorder that may interfere with the patient's cognition or ability to perform the study procedures. * Use of Memantine Hydrochloride within 1 month prior to screening