Donepezil (EP,USP)

Main application: 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. 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. Donepezil is a parasympathomimetic, specifically, a reversible cholinesterase inhibitor. 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. There is no evidence that donepezil alters the course of the underlying dementing process.