The road to discovering and developing new drugs to treat Alzheimer’s disease (AD) is long and difficult. Ideally, an effective AD drug will do several things: benefit many patients for a long time, slow down or stop the disease, improve patients’ mental abilities and functioning in activities of daily living, and have few serious side effects.
Tacrine (trade name Cognex) and donepezil (trade name Aricept) are the only drugs that the Food and Drug Administration (FDA) has approved so far to treat some symptoms of AD.
An important first step in developing these drugs was the discovery that the brains of AD patients have a shortage of acetylcholine. Acetylcholine is a chemical messenger or neurotransmitter that aids communication between neurons in the brain, especially those responsible for learning and memory. Drugs like tacrine and donepezil increase the brain’s supply of acetylcholine, allaying some symptoms and helping brain cells function more efficiently in some patients.
Researchers now believe that the brain deficit of acetylcholine may not be a central event in AD, but only one of a cascade of biochemical events, some of which cause brain cells to die. Several other medications that enhance or mimic the action of acetylcholine in the brain are in the later stages of the FDA drug-approval process. These other cholinergic drugs may prove to be more effective or have fewer side effects than either tacrine or donepezil.
However, many researchers believe that any cholinergic drug will offer only moderate and temporary benefits. Therefore, they are searching for new treatments that prevent cell death; neither tacrine nor donepezil does this.
Source: Connections Magazine [Volume 6(1), Spring 1997]
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