|Systematic (IUPAC) name|
|Legal status||℞ Prescription only|
|Routes||Oral tablet, 5,10 & 23mg|
|Mol. mass||379.492 g/mol|
| (what is this?)
Donepezil, marketed under the trade name Aricept by its developer Eisai and partner Pfizer, is a centrally acting reversible acetylcholinesterase inhibitor. Its main therapeutic use is in the palliative treatment of mild to moderate Alzheimer's disease. Common side effects include gastrointestinal upset. It has an oral bioavailability of 100% and easily crosses the blood–brain barrier. Because it has a half-life of about 70 hours, it can be taken once a day.
Medical uses 
Alzheimer's disease 
Currently, no definitive proof shows the use of donepezil or other similar agents alters the course or progression of Alzheimer's disease (AD). However, 6 to 12-month controlled studies have shown modest benefits in cognition and/or behavior. Pilot studies have reported donepezil therapy may potentially have effects on markers of disease progression, such as hippocampal volume. Therefore, many neurologists, psychiatrists, and primary-care physicians use donepezil in patients with Alzheimer's disease. In 2005, the UK National Institute for Clinical Excellence (NICE) withdrew its recommendation for use of the drug for mild-to-moderate AD, on the basis of no significant improvement in functional outcome, quality of life, or behavioral symptoms. However, NICE revised its guidelines to suggest donepezil be used in moderate-stage patients for whom the evidence is strongest.
While the drug is currently indicated for mild to moderate Alzheimer's, evidence from two clinical trials also indicates it may be effective for moderate to severe disease. An example of this is a Karolinska Institute paper published in The Lancet in early 2006, which states donepezil improves cognitive function even in patients with severe AD symptoms.
In mild to moderate Alzheimer’s Disease, a starting dose of 5 mg given once daily should be used. In a minimum of four to six weeks, an increase to 10 mg is recommended. The usual dose is 5 to 10 mg once daily. Moderate to severe AD indicates the same regimen, but in a minimum of three months, a patient may receive a dose of 23 mg once daily. Dementia patients should receive 5–10 mg once daily. The maximum daily dose is 23 mg once daily. Clinicians should use caution in prescribing the maximum daily dose as the risk of severe side effects may outweigh the unclear clinical benefits. In the UK, the maximum licensed dose is 10 mg.
Donepezil (Aricept) should be used with caution in patient with cardiac disease, cardiac conduction disturbances, chronic obstructive pulmonary disease, asthma, severe cardiac arrhythmias and sick sinus syndrome. Patients with gastrointestinal disorders should use caution because nausea or vomiting may occur. These symptoms may appear more frequent when initiating treatment or increasing the donepezil dose. Although occurrence of seizures is rare, patients who have a predisposition to seizures should be treated with caution. The British Medical Journal (BMJ) cautioned that the largest dosage, 23 mg, was crafted to extend patent protection rather than for medical reasons, and was not shown to be more effective compared to the 10 mg dose.
Donepezil has been tested (off label) in other cognitive disorders, including Lewy body dementia, and vascular dementia, but it is not currently approved for these indications. Donepezil has also been found to improve sleep apnea in Alzheimer's patients.
Donepezil has also been studied in patients with mild cognitive impairment, schizophrenia, attention deficit disorder, postcoronary bypass cognitive impairment, cognitive impairment associated with multiple sclerosis, CADASIL syndrome, and Down syndrome. A three-year National Institutes of Health trial in patients with mild cognitive impairment reported donepezil was superior to placebo in delaying rate of progression to dementia during the initial 18 months of the study, but this was not sustained at 36 months. In a secondary analysis, a subgroup of individuals with the apolipoprotein E4 genotype showed sustained benefits with donepezil throughout the study (Petersen 2005). At this time, though, donepezil is not indicated for prevention of dementia.
Recent studies suggest donepezil can improve speech in children with autism. The studies found the speech of autistic children who were mildly to moderately affected appeared to improve from the use of donepezil.
Adverse effects 
Common side effects include bradycardia, nausea, diarrhea, anorexia, abdominal pain, and vivid dreams. In 2006 Eisai, the manufacturer, issued a statement that a single vascular dementia study found a difference in the percentage of study participants who died in the donepezil group (1.7%) versus the placebo group (0%), and this could be due to an unusually low death rate on the placebo group. An analysis of all three vascular dementia trials, according to Eisai, "shows no statistically significant differences in observed mortality rates between the donepezil and placebo groups." A physician has reported several cases of mania.
Development and marketing 
Research leading to the development of donepezil began in 1983 at Eisai, and the first Phase I clinical trial took place in 1989. In 1996, Eisai received approval from the United States Food and Drug Administration (USFDA) for donepezil under the brand Aricept, which it co-marketed with Pfizer. As of 2011, Aricept was the world's best-selling Alzheimer's disease treatment. The first generic donepezil became available in November 2010 with the USFDA approval of a formulation prepared by Ranbaxy Labs. In April 2011 a second generic formulation, from Wockhardt, received tentative USFDA marketing approval.
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- LA Times, 2012-03-22 New Alzheimer's Pill Likely To Cause Misery
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- Sugimoto, Hachiro; Ogura, Hiroo; Arai, Yasuo; Iimura, Youichi; Yamanishi, Yoshiharu (25 January 2002), "Research and Development of Donepezil Hydrochloride, a New Type of Acetylcholinesterase Inhibitor", The Japanese Journal of Pharmacology (2002) 89 (1): 7–20, doi:10.1254/jjp.89.7, retrieved 25 April 2011
- Kanoko Matsuyama (25 April 2011). "Eisai Aricept Patch for Alzheimer’s Isn’t Ready for Approval". Bloomberg. Retrieved 25 April 2011.
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- Acting Editor-in-Chief Louise Welbanks. (2000). Compendium of Pharmaceuticals and Specialities, 2000 (25th ed.). Canadian Pharmaceutical Assn. ISBN 0-919115-76-4.
- Official Aricept product site
- Aricept entry at Drugs.com
- 3D Molecular structure of Donepezil
- Donepezil bound to proteins in the PDB