Recent developments in natural and synthetic drug research for Alzheimer's disease

Alzheimer's Disease (AD) is a progressive and degenerative neurological disorder characterized by loss of cognition and memory. However, the pathogenesis of AD is still not clearly known. Current research in drug discovery for treatment of AD involves various targets, being only symptomatic, with the main therapeutic strategies based on "cholinergic hypothesis" and "amyloid cascade hypothesis". During the last decade, inhibitors of acetylcholinesterase (AChE) such as tacrine (Cognex(R)), donepezil (Aricept(R)). rivastigmine (Exelon(R)), and galanthamine (Reminyl(R)) have been launched. More recently, memantine (Ebixa(R)) has been emerged on the market as an N-methyl-D-aspartate (NMDA) receptor antagonist, which has been approved to be effective in the treatment of moderate to severe type of AD. In this review, we will focus on recent status of drug molecules for treatment of AD, currently either that in clinical practice. or still in clinical trials.