While Alzheimer’s disease (AD) has no cure, five prescription medicines have been approved by the U.S. Food and Drug Administration (FDA) to treat disease symptoms that impact thinking and memory.
Three of these medications, Aricept (donepezil), Razadyne (galantamine), and Exelon (rivastigmine), are cholinesterase inhibitors, which work by increasing levels of acetylcholine, a chemical messenger that is involved in memory, judgment, and other thought processes. A fourth, Namenda (memantine), regulates the activity of glutamate, a chemical involved in processing, storing and retrieving information. A combination of donepezil and memantine is the final approved medicine and is known by its brand name, Namzaric.
Cholinesterase inhibitors are prescribed to help with memory, thinking, language, judgment, and other thought processes.
Aricept is approved for all stages of AD, while Razadyne and Exelon are approved for the treatment of mild-to-moderate AD.
Alzheimer’s damages cells that produce acetylcholine, which reduces the amount of this chemical (a neurotransmitter) available to carry messages to other brain cells. Cholinesterase inhibitors slow the breakdown of acetylcholine, helping to maintain higher levels that compensate the loss of properly working brain cells.
Cholinesterase inhibitors may also have other benefits, with galantamine, for instance, being thought to stimulate acetylcholine release and promote how certain nerve cells respond to this chemical messenger.
Because Alzheimer’s is a progressive disease and these drugs do not affect underlying disease processes, their effectiveness is likely to diminish as the disease advances and more brain cells are damaged.
Side effects of cholinesterase inhibitors can include nausea, vomiting, loss of appetite, and more frequent bowel movements.
Namenda, approved to treat moderate-to-severe AD, is given Alzheimer’s patients to help with memory, attention, reasoning, language, and the ability to perform simple tasks.
The drug is known as a NMDA (for N-Methyl-D-aspartate) receptor antagonist, and works by regulating glutamate activity. Glutamate has an essential role in learning and memory; the chemical works to allow precise amounts of calcium into nerve cells, facilitating information being stored. But excess calcium damages cells, and Namenda is thought to also help protect cells against excess glutamate by partly blocking receptors.
Side effects of its use can include headaches, constipation, confusion, and dizziness.
Namzaric is a combination of memantine and donepezil also approved to treat moderate-to-severe AD.
It may help to improve cognition and overall mental abilities, and to temporarily slow the worsening of AD symptoms.
Potential side effects of Namzaric include a slower heartbeat and fainting, especially in patients with cardiac problems; increased stomach acid, raising a risk of ulcers; nausea and vomiting; difficulty urinating; seizures; muscle problems in people being given anesthesia; and a worsening of lung problems in people with asthma or other lung diseases.
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