ACHE and Alzheimer disease: Presently, the US Food and Drug Administration (FDA) has approved five drugs in three sub-classes for the treatment of AD including acetylcholinesterase (AChE) inhibitor (rivastigmine, galantamine, and donepezil), N-methyl D aspartate receptor (NMDA) antagonist (memantine), and a combined drug between AChE inhibitor and NMDA receptor antagonist (Namzaric®) [6].