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Information |
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Drug Groups
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approved |
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Description
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Donepezil (Aricept), is a centrally acting reversible acetyl cholinesterase inhibitor. Its main therapeutic use is in the treatment of Alzheimer's disease where it is used to increase cortical acetylcholine. Donepezil is postulated to exert its therapeutic effect by enhancing cholinergic function. This is accomplished by increasing the concentration of acetylcholine through reversible inhibition of its hydrolysis by acetylcholinesterase. If this proposed mechanism of action is correct, donepezil's effect may lessen as the disease process advances and fewer cholinergic neurons remain functionally intact. Donepezil has been tested in other cognitive disorders including Lewy body dementia and Vascular dementia, but it is not currently approved for these indications. Donepezil has also been studied in patients with Mild Cognitive Impairment, schizophrenia, attention deficit disorder, post-coronary bypass cognitive impairment, cognitive impairment associated with multiple sclerosis, and Down syndrome. |
| Indication |
For the palliative treatment of mild to moderate dementia of the Alzheimer's type. |
| Pharmacology |
Donepezil is a centrally acting reversible acetyl cholinesterase inhibitor. Its main therapeutic use is in the treatment of Alzheimer's disease where it is used to increase cortical acetylcholine. An early pathophysiological feature of Alzheimer's disease that is associated with memory loss and cognitive deficits is a deficiency of acetylcholine as a result of selective loss of cholinergic neurons in the cerebral cortex, nucleus basalis, and hippocampus. Donepezil is postulated to exert its therapeutic effect by enhancing cholinergic function. This is accomplished by increasing the concentration of acetylcholine through reversible inhibition of its hydrolysis by acetylcholinesterase. If this proposed mechanism of action is correct, donepezil's effect may lessen as the disease progresses and fewer cholinergic neurons remain functionally intact. There is no evidence that donepezil alters the course of the underlying dementing process. |
| Toxicity |
Symptoms of overdose include severe nausea, vomiting, salivation, sweating, bradycardia, hypotension, respiratory depression, collapse and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. |
| Affected Organisms |
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Humans and other mammals |
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| Biotransformation |
Donepezil is metabolized by CYP 450 isoenzymes 2D6 and 3A4 in the liver and also undergoes glucuronidation. The main metabolite, 6-O-desmethyl donepezil, has been reported to inhibit AChE to the same extent as donepezil in vitro. |
| Absorption |
Donepezil is well absorbed with a relative oral bioavailability of 100% and reaches peak plasma concentrations in 3 to 4 hours. |
| Half Life |
70 hours |
| Protein Binding |
96% |
| Elimination |
Donepezil is both excreted in the urine intact and extensively metabolized to four major metabolites, two of which are known to be active, and a number of minor metabolites, not all of which have been identified. |
| Distribution |
* 12 L/kg |
| Clearance |
* apparent plasma cl=0.13 L/hr/kg |
| References |
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Xiong G, Doraiswamy PM: Combination drug therapy for Alzheimer's disease: what is evidence-based, and what is not? Geriatrics. 2005 Jun;60(6):22-6.
[Pubmed]
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Yesavage JA, Mumenthaler MS, Taylor JL, Friedman L, O'Hara R, Sheikh J, Tinklenberg J, Whitehouse PJ: Donepezil and flight simulator performance: effects on retention of complex skills. Neurology. 2002 Jul 9;59(1):123-5.
[Pubmed]
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Sugimoto H: Donepezil hydrochloride: a treatment drug for Alzheimer's disease. Chem Rec. 2001;1(1):63-73.
[Pubmed]
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