January 27, 2023
Research findings disclosed for dementia are extendable to many other neurodegenerative diseases. For brevity, the drug R&D for Alzheimer's disease (AD) is selected as an instructive example.
Donepezil, Rivastigmine, Galantamine, and Memantine are four well-known drugs for treating AD, approved by the FDA in 1996, 2000, 2001, and 2003, respectively. Despite significant efforts, none of the four drugs has found therapeutic mechanisms. In other words, people still need to understand the underlying causes behind their efficacies and effectiveness clearly.
Did scientists fail to discover the neuroprotectants and neurotoxins contributing to AD during this period? The answer is no. A considerable portion of their work on basic science has been on the right track. The critical point is that there was no technology or foundation to connect scientific discoveries to the drugs in clinical practices precisely.
It is necessary to point out that neuroscience is not alone in this awkward situation. Due to the advent of the new technology introduced on the front page, the challenge is becoming an opportunity for advancement. For neuroscience, finding and evaluating more neuroprotectants and neurotoxins in specific zones of the human brain are essential in new investigations.
The four drugs are independent of each other based on their dependencies on the following factors:
• The endogenous neuroprotectant family one drug belongs to. In other words,
the effective drug is a member of a particular neuroprotectant group.
• The types of neurotoxins that the drug neutralizes.
• The target locations/zones in the brain the drug anchors on.
• The solubility property that the drug possesses.
There are highly complicated and susceptible systems in the human brain to support unimaginable operations for homeostasis. Hence, any subtle variation of one factor above will likely lead to different therapeutic reactions. For example, some commercial drugs on the market are close family members of Galantamine with moderate solubility variations, and they are used to treat Amyotrophic Lateral Sclerosis (ALS), Parkinson's Disease (PD), Myasthenia Gravis, Osteoarthritis, Overweight & Obesity, Alcohol Dependence, etc.
Two kinds of new investigational drugs relevant to AD are emerging in clinical trials. Their novelties are rooted primarily in unprecedented target zones in the CNS and less noticeable neurotoxins.
Few commercial drugs act with a single therapeutic function. As a result, abundant opportunities exist to repurpose many commercial medicines to treat neurodegenerative diseases through clinical trials and progressive exploration of new drug candidates.