Cholinesterase inhibitors for Alzheimer's disease

Examples

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Brand Name	Generic Name
Aricept	donepezil

Brand Name	Generic Name
Razadyne	galantamine

Brand Name	Generic Name
Exelon	rivastigmine

How It Works

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Cholinesterase inhibitors increase the level of a brain chemical called acetylcholine. People with Alzheimer's disease and related conditions have decreased brain levels of this neurotransmitter. Increasing the amount of acetylcholine appears to slow mental decline in people with Alzheimer's disease.

These medicines help the brain cells work better but do not stop or reverse the destruction of brain cells and loss of acetylcholine that occur in Alzheimer's disease. They do not prevent the disease from getting worse but may slow the progression of symptoms.

Why It Is Used

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Cholinesterase inhibitors may be used to treat some symptoms of Alzheimer's disease. They also may be used in other types of dementia, such as dementia with Lewy bodies and multi-infarct dementia.

How Well It Works

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Cholinesterase inhibitors may produce small improvements in memory and general ability to function.¹ For example, the person may be able to remember friends' names better and be able to dress himself or herself with less difficulty.

• Studies have shown that people with mild to moderately severe Alzheimer's who took donepezil scored somewhat higher in their doctors' evaluations of their mental and functional status than those who did not take the drug.¹
• Studies show that rivastigmine has beneficial effects similar to donepezil. Rivastigmine has more side effects, including nausea and possible weight loss. Because of the side effects, more people stop treatment with rivastigmine.¹
• Galantamine is available in the United States. It may improve memory and thinking abilities.
• Improvement with cholinesterase inhibitors usually is minimal. The person's mental status does not stabilize, but the rate of decline may be somewhat slower than it would be without the medicine.
• Improvement in symptoms may be more likely at higher doses, but higher doses also may cause more side effects.
• Doctors don't know for sure that cholinesterase inhibitors help with behavior problems in people who have Alzheimer's disease². Some studies show that these medicines do help, which can mean less burden on caregivers.³ But other studies show that these medicines do not help.^{4 5}
• Cholinesterase inhibitors may have some use in other dementias, such as dementia with Lewy bodies and multi-infarct dementia.

Cholinesterase inhibitors do not help everyone who has Alzheimer's disease. It is believed that as the disease progresses, the medicine eventually may stop working.

The various cholinesterase inhibitors have similar effects on memory and cognitive function, so the choice between medicines may be based on side effects, dosing schedules and ease of use, individual response to a particular medicine, or other factors.

Side Effects

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In general, most people seem to tolerate cholinesterase inhibitors very well. The most common side effects are:

• Nausea.
• Diarrhea.
• Vomiting.
• Indigestion.
• Abdominal pain.
• Loss of appetite and weight loss.

Less common side effects include insomnia, fatigue, and muscle cramps. Side effects tend to be mild and usually go away within a few weeks after treatment with the medicine is started.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

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Cholinesterase inhibitors do not work for everyone who has Alzheimer's disease, but they are helpful for some people. They may be a reasonable option for those who understand the risks and costs and feel the possible benefits are worth it.

Most studies of cholinesterase inhibitors for people with Alzheimer's disease found that the benefits of taking these medicines are small.^{6 4}

Side effects seem to be milder and occur less often with donepezil or galantamine than with rivastigmine.

Experts agree that reducing problems with memory loss may help people with Alzheimer's disease live better. In some cases, reducing these problems may help people live more independently for a longer period of time.

Rivastigmine (Exelon) can now be given through a skin patch. Skin patches release medicine into the blood at a steady level and may reduce side effects. And it’s easier for caregivers to make sure a person is taking the medicine properly when the person uses a skin patch.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.

References

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Citations

1. Warner J, et al. (2008). Dementia, search date February 2006. Online version of BMJ Clinical Evidence. Also available online: http://clinicalevidence.com.

2. Sink KM, et al. (2005). Pharmacological treatment of neuropsychiatric symptoms of dementia: A review of the evidence. JAMA, 293(5): 596–608.

3. Trinh NH, et al. (2003). Efficacy of cholinesterase inhibitors in the treatment of neuropsychiatric symptoms and functional impairment in Alzheimer disease: A meta-analysis. JAMA, 289(2): 210–216.

4. Raina P, et al. (2008). Effectiveness of cholinesterase inhibitors and memantine for treating dementia: Evidence review for a clinical practice guideline. Annals of Internal Medicine, 148(5): 379–397.

5. Howard RJ, et al. (2007). Donepezil for the treatment of agitation in Alzheimer's disease. New England Journal of Medicine, 357(14): 1382–1392.

6. Kaduszkiewicz H, et al. (2005). Cholinesterase inhibitors for patients with Alzheimer's disease: Systematic review of randomised clinical trials. BMJ, 331(7512): 321–327.

Credits

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Author	Monica Rhodes
Editor	Kathleen M. Ariss, MS
Associate Editor	Pat Truman, MATC
Primary Medical Reviewer	Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer	Peter J. Whitehouse, MD - Neurology
Last Updated	November 10, 2008