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Alzheimer's Medications
(Part 1), the Cholinesterase Inhibitors
by
Becky Sisk, PhD, RN
©
Revised 2004
There is no cure for Alzheimer's disease. However, several medications alleviate early cognitive symptoms.
Recall that the basic problem in Alzheimer's disease is structural damage
to brain cells, resulting in amyloid plaques and neurofibrillary tangles. Amyloid plaques are deposits of a
substance called beta-amyloid, which are toxic to neurons. Neurofibrillary tangles are made up of a substance called
tau. Tau exists normally in brain cells, but, in Alzheimer's disease, it forms abnormal, twisted threads--the neurofibrillary
tangles--that interfere with the neuron's ability to transport messages.
Acetylcholine, a neurotransmitter that facilitates
the activity from one neuron to the next, is markedly decreased in Alzheimer's disease. Cholinesterase, an enzyme, normally
breaks down acetylcholine. The drugs currently approved by the FDA for Alzheimer's disease are "cholinesterase
inhibitors," which slow this breakdown process.
The FDA-approved drugs for Alzheimer's disease are tacrine
(Cognex), donepezil (Aricept), rivastigmine (Exelon), and galantamine (Reminyl). These drugs are given to people in the early stages of Alzheimer's disease and are not curative. They slow the memory and cognitive impairments
characteristic of Alzheimer's disease. Usual doses are as follows:
|
Medication |
Dose |
Precautions* |
| Donepezil (Aricept) |
5-10 mg. orally per day, usually given at bedtime
|
May interact with cimetidine (Tagamet), digoxin (Lanoxin),
and theophylline |
| Rivastigmine (Exelon) |
Increased over several weeks from 1.5 mg to eventual
dose of 6-12 mg orally per day |
May cause weight loss
May interact with
aminoglycosides or procainamide (Procanbid) |
| Galantamine (Reminyl)
|
Gradually increased from 8 mg. orally to 16 mg. orally per
day |
Contraindicated if patient has kidney or liver problems |
|
Tacrine (Cognex) |
10 mg. orally, four times per day, Gradually increased over
several weeks to 40 mg four times per day, as tolerated |
May interact with procainamide or theophyline
May cause liver damage
No longer considered a
drug of choice for Alxzheimer's disease (Cummings et al.,
2002) |
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*Side effects of these drugs include anorexia, nausea, vomiting, and diarrhea. In addition to cholinesterase inhibitors,
antioxidants, such as vitamin E, are given to remove free radicals, metabolic byproducts that appear to cause cell
damage in the aging process.
Reference:
Cummings, J.L., Drank, K.C., Cherry, D.,
Kohatsu, N.D., Kemp, B., Hewett, L. & Mittman, B. (2002). Guidelines for
managing Alzheimer's disease. American Family Physician, 65(12):
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