Donepezil Hydrochloride is a centrally acting anticholinesterase agent. It binds reversibly with acetylcholinesterase and inactivates it, thus inhibiting hydrolysis of acetylcholine. As a result the concentration of acetylcholine increases at cholinergic synapses in the brain.

Donepezil is indicated for the symptomatic treatment of mild to moderate dementia of Alzheimer's type.

5 mg once daily orally at bed time. The 5 mg/day dose should be maintained for at least one month in order to allow the earliest clinical responses to treatment to be assessed and to allow steady-state concentrations of donepezil hydrochloride to be achieved. Following a one-month clinical assessment of treatment at 5 mg/day, the dose can be increased to 10 mg/day (once-a-day dosing). Since food does not affect the rate or extent of absorption of donepezil, it can be administered with or without food.

Donepezil is contraindicated in patients with known hypersensitivity to donepezil hydrochloride or to piperidine derivatives.

Generally well tolerated but some patients may experience nausea, vomiting & diarrhoea. These adverse events are of mild intensity and transient, resolving during continued treatment without the need for dose modification. Less frequent side effects are insomnia, fatigue, anorexia, muscle cramps, generalized seizure etc.

Overdose Effects

Symptoms of overdose includes nausea, vomiting, salivation. Over dosage with very high dose of donepezil may result in cholinergic crisis characterized by severe nausea, vomiting, salivation, bradycardia, hypotension, increasing muscle weakness, respiratory depression, collapse and convulsion. As in any case of over dose, general supportive measures should be utilized. In case of cholinergic crisis hospitalization of the patient is required.

Caution should be taken in sick sinus syndrome or other supraventricular conduction abnormalities, patients at risk of developing peptic ulcers, asthma, obstructive airway disease and during anaesthetic procedure.

Use in Special Populations

Renal & hepatic impairment: A similar dose schedule can be followed for patients with renal or mild to moderate hepatic impairment as clearance of donepezil hydrochloride is not affected by these conditions.

Use in children: There are no adequate and well controlled trials in document to safety and efficacy of Donepezil hydrochloride in any illness occurring in children. Donepezil is not recommended for use in children.

Pregnancy & Lactation

There are no adequate and well controlled studies in pregnant woman. Donepezil should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is not known whether Donepezil Hydrochloride is secreted in human breast milk or not. Donepezil is not indicated in nursing mother.