Exelon (rivastigmine), developed by Novartis Pharmaceuticals, is an approved treatment for mild to moderate dementia that is caused by Parkinson’s and Alzheimer’s disease. It works to improve nerve cell function in the brain, and belongs to a group of drugs called cholinesterase inhibitors.
How Exelon works
Nerve cells communicate with one another and with muscle cells using signaling molecules called neurotransmitters; as these molecules are released from nerve cells they diffuse to neighboring cells, stimulating a response upon arrival. One such signaling molecule is acetylcholine, released by nerve cells via synapses to muscle cells so as to trigger a reaction, like muscle contraction. But once the neurotransmitter’s signal has been delivered, the molecule must be destroyed so as not to confuse later signals.
Acetylcholinesterase is found in the synapse between nerve cells and muscle cells. It acts soon after a signal is passed to break down acetylcholine molecules and allow their recycling, effectively stopping the signal.
Dementia, however, is marked by damaged or lost nerve cells and low levels of acetylcholine in patients’ brains. Exelon works to inhibit acetylcholinesterase, and by blocking it prevent the breakdown of acethylcholine to strengthen nerve signals still taking place.
Exelon in clinical trials
Exelon was approved by the U.S. Food and Drug Administration (FDA) in 2000 to treat Alzheimer’s and Parkinson’s disease-related dementia. This approval was based on the results of three clinical trials in Alzheimer’s disease and one controlled trial in dementia associated with Parkinson’s disease.
For Parkinson’s-associated dementia, Exelon was tested in a 24-week randomized, double-blind, placebo-controlled clinical trial in 541 patients, with efficacy assessed by clinical benefit recorded in cognition by Alzheimer’s Disease Cooperative Study – Clinician’s Global Impression of Change (ADCS-CGIC) scores.
Patients were randomized to a dose range of 3 to 12 mg of Exelon daily or placebo for 16 weeks, then to maintenance treatment for eight weeks at their highest tolerable dose. Results after 24 weeks of treatment found a significant mean difference of 0.5 in ADCS-CGIC scores in treated patients compared to placebo, and a mean, significant difference of 3.8 in the Alzheimer’s disease assessment scale (ADAS-cog), again for treated patients compared to those given placebo.
Exelon is available as a capsule or solution to be taken by mouth or, since 2007, as a transdermal skin patch. The Exelon patch may be of benefit to people susceptible to gastrointestinal problems or able to swallow effectively. Patches also can help physicians, family members, and caregivers confirm that the medication has been taken.
Common side effects of Exelon use can include upset stomach, nausea, vomiting, diarrhea, loss of appetite or weakness.
The potential beneficial effect of Exelon could lessen as the disease progresses, and fewer nerve cells are working to release acetylcholine.
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