by Dr. Manura Nanayakkara

Created on: July 21, 2010   Last Updated: September 24, 2010

Donepezil is a drug prescribed in dementia including Alzheimer’s disease. It is an Acetyl choline esterase inhibitor. But this drug only slows down the progression of disease and it will not cure the dementia.  Most common brand name is Aricept® by Pfizer pharmaceuticals.

Overview of dementia and the mechanism of action

Dementia in Alzheimer’s disease is caused by selective destruction of Acetyl Choline secreting neurons and the associated reduction in Acetyl choline neurotransmission.  Acetyl choline esterase inhibitors like Donepezil increase acetyl choline levels in surviving neurons. Ultimately this drug will fail to improve symptoms, because of the reduction in the surviving neurons that secrete Acetyl choline.

What are the dangerous side effects that need emergency treatment?

Some patients can get severe allergic reaction called an anaphylactic reaction. If a patient develops wide spread hives, shortness of breath, chest tightness and edema of lips and mouth then he/she must stop the drug and seek emergency medical help.

In addition, some patients can develop gastro intestinal bleeding. So if a patient is starting to pass tarry stools and blood stained vomiting, emergency medical advice must be sought. Sometimes this medication can cause fits (seizures) as well.

What are the common but less dangerous side effects?

Nausea, Vomiting, loss of appetite and diarrhea are the commonest side effects. Fatigue and sleep disturbances are also common.  Some patients may get a headache with this drug. Certain patients may get dizzy and can faint. Few patients may experience hallucinations. Agitation and aggression can be troublesome side effect for the care givers. Muscle cramps and urinary incontinence can occur with certain patients. Itchy rashes are also a side effect.

What are the rare side effects?

Stomach and duodenal ulcers can occur rarely. Gastro intestinal hemorrhage can be a dangerous side effect. If a patient gets blackish stools and bloody vomiting, then medical advice must be sought immediately. Reduced heart rate, fits, liver destruction and movement problems are quite rare side effects.

What the doctor should know before prescribing Donepezil?

Patient/caregiver must discuss with the doctor, if the patient has following diseases.

1. Sick sinus syndrome

2. Supraventricular tachycardia

3. Stomach ulcers

4. Bronchial asthma

5. Chronic obstructive pulmonary disease (COPD)

6. Liver disease

7. Epilepsy

Before prescribing, the doctor should know the drugs patient is taking including all the over the counter and herbal medications. Drugs that increase Acetyl choline action may cause dangerous interactions with this drug.

If the patient is undergoing surgery, anesthetic doctor must know that he/she is taking Donepezil, because certain anesthetic injections can have dangerous interactions with this drug. In addition, prescribing doctor should know whether the patient is pregnant. Other than that, this drug must not be taken by nursing mothers.

This drug is available as conventional as well as orally disintegrating tablets.  Conventional tablets should be taken with a full glass of water as prescribed by the doctor. 

Disintegrating tablets should be kept in the mouth, until it is dissolved. After that a full glass of water should be taken. In addition, this drug can be taken without regard to meals.

Sources

BNF

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