Overview
Donepezil is a centrally acting, reversible acetylcholinesterase inhibitor. It is a primary pharmacological treatment for Alzheimer’s disease, indicated for the symptomatic management of mild, moderate, and severe dementia, aiming to improve or stabilize cognitive function and daily activities.

Mechanism of Action
Alzheimer’s disease is characterized by a significant deficiency in acetylcholine, a neurotransmitter crucial for memory and learning. Donepezil inhibits acetylcholinesterase, the enzyme that breaks down acetylcholine in the synaptic cleft. This action increases the concentration of acetylcholine in the brain, temporarily enhancing cholinergic neurotransmission.

Dosage and Administration
The initial dose is 5 mg once daily, typically taken in the evening just before bedtime. After 4 to 6 weeks, the dose may be increased to 10 mg daily for optimal therapeutic effect. It can be taken with or without food.

Side Effects
Common side effects are primarily cholinergic in nature and include nausea, vomiting, diarrhea, loss of appetite, and muscle cramps. It can also cause vivid dreams, insomnia, and bradycardia (slow heart rate). These side effects are often mild and transient, resolving with continued use.

Contraindications
It is contraindicated in patients with a known hypersensitivity to donepezil or piperidine derivatives. Caution is advised in patients with sick sinus syndrome, supraventricular cardiac conduction conditions, a history of peptic ulcer disease, or a history of seizures.

Pregnancy and Lactation
There are no adequate and well-controlled studies in pregnant women. Donepezil should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is not known whether donepezil is excreted in human breast milk.