Aricept
Donepezil, marketed under the trade name Aricept® (Eisai), 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. It is well absorbed in the gut with 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. Initial dose is 5 mg per day, which can be increased to 10 mg per day after an adjustment period of at least 4 weeks.

The clinical utility of donepezil is controversial. Presently, there is no proof that use of donepezil or other similar agents alters the course or progression of Alzheimer's disease. However, controlled studies have shown modest benefits in cognition and behavior with this and similar agents. Therefore, many neurologists, psychiatrists, and primary care physicians use donepezil in patients with Alzheimer's disease. As of the 22 March 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 that there is no significant improvement in functional outcome; of quality of life or of behavioral symptoms. However, these data conflict with those of other reports, as is often the case in medicine.

Donepezil is sometimes used in combination with Memantine, a new agent for Alzheimer's disease which is in the same chemical class. The response to both together is superior to either alone.

Donepezil has been tested in other disorders which cause dementia including Lewy body dementia and Vascular dementia, but it is not currently approved for these indications.