BMA Concise Guide to Medicine & Drugs

Donepezil

Brand name Aricept

Used in the following combined preparations None

QUICK REFERENCE

Drug group Drug for dementia

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Donepezil is an inhibitor of the enzyme acetylcholinesterase. This enzyme breaks down the natural neurotransmitter acetylcholine to limit its effects. Blocking the enzyme raises levels of acetylcholine, which, in the brain, increases awareness and memory. Donepezil has been found to improve the symptoms of dementia in Alzheimer’s disease and is used to diminish deterioration in that disease. It is not currently recommended for dementia due to other causes. Treatment with donepezil is initiated under specialist supervision. It is usual to assess those being treated at six monthly intervals to decide whether the drug is helping.

Side effects may include bladder outflow obstruction and psychiatric problems, such as agitation and aggression, which might be due to the disease.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Once daily at bedtime.

Adult dosage range 5–10mg.

Onset of effect 1 hour. Full effects may take up to 3 months.

Duration of action Usually 1–2 days.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. A carer should ensure that the maximum dose taken in 24 hours does not exceed 10mg.

Stopping the drug Do not stop taking the drug without consulting your doctor; symptoms may recur.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.

POSSIBLE ADVERSE EFFECTS

Adverse effects include such problems as accidents, which are common in people with dementia, even those not being treated. Other adverse effects include nausea, vomiting, diarrhoea, fatigue, insomnia, muscle cramps, and headache. Consult your doctor if any of these are severe. You should also consult your doctor if you experience urinary incontinence or difficulty in passing urine, fainting, dizziness, or palpitations. If you have seizures, stop taking the drug and seek urgent medical help.

INTERACTIONS

Muscle relaxants used in surgery Donepezil may increase the effect of some muscle relaxants, but it may also block some others.

Fluoxetine, erythromycin and ketoconazole can increase the levels and adverse effects of donepezil.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have liver or kidney problems.

· You have a heart problem.

· You have asthma or respiratory problems.

· You have had a gastric or duodenal ulcer.

· You are taking an NSAID regularly.

· You are taking other medicines.

Pregnancy Not recommended. Safety in pregnancy not established.

Breast-feeding Not recommended.

Infants and children Not recommended.

Over 60 No special problems.

Driving and hazardous work Your underlying condition may make such activities inadvisable. Discuss with your doctor.

Alcohol Avoid. Alcohol may reduce the effect of donepezil.

Surgery and general anaesthetics Treatment with donepezil may need to be stopped before you have a general anaesthetic. Discuss this with your doctor or dentist before any operation.

PROLONGED USE

May be continued for as long as there is benefit. Stopping the drug leads to a gradual loss of the improvements over several weeks.

Monitoring Periodic checks should be carried out at 6-monthly intervals to test whether the drug is still providing some benefit.