January 27, 2023
Research findings disclosed for dementia are applicable 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 the treatment of AD, approved by the FDA in 1996, 2000, 2001, and 2003, respectively. In the last twenty years, none of the four drugs was insightfully identified by their therapeutic functions. In other words, people do not yet clearly understand the underlying causes behind their efficacies and effectiveness.
Have scientists failed to find out the neuroprotectants and neurotoxins that contribute to AD during this period of time? The answer is no. A considerable portion of their work on basic science has been on the right track. The key point is that there was no technology or foundation to precisely connect scientific discoveries to the drugs in clinical practices.
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, it is of critical importance to find and evaluate more neuroprotectants and neurotoxins in specific zones of the human brain.
The four drugs are independent of each other, based on their dependencies on the following factors
• The endogenous neuroprotectant family that one drug belongs to. In other words, an effective
drug is a member of a particular neuroprotectant group.
• The types of neurotoxins that the drug neutralizes.
• The exact target locations/zones in the brain that the drug anchors on.
• The solubility property that the drug possesses.
There are highly complicated and very sensitive systems in the human brain to support unimaginable operations for homeostasis, any subtle variation of one factor above is likely to lead to quite 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 types of new investigational drugs relevant to AD are emerging in clinical trials and 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 and hence many drugs can be repurposed to treat neurodegenerative diseases through clinical trials in addition to a progressive exploration of new drug candidates.