Donepezil
2 medicines
Donepezil eases Alzheimer's symptoms by boosting a brain chemical, but it slows heart rate through the same mechanism and can cause dangerous bradycardia or fainting, especially with other heart-rhythm medicines.
Key facts
- Donepezil is a cholinesterase inhibitor that increases the amount of acetylcholine, a nerve-signaling chemical involved in memory, available in the brain. It is sold under names such as Aricept and is also combined with memantine in Namzaric.
- It is taken once daily, usually at bedtime, and doses are increased slowly over weeks to reduce stomach side effects.
- Because acetylcholine also slows the heart, donepezil can cause a dangerously slow heart rate, fainting, or heart block, particularly with existing conduction problems or other heart-rate-lowering medicines.
- Seek urgent care for fainting, a very slow or irregular pulse, or a seizure.
What donepezil treats
Donepezil treats the memory loss and thinking difficulties of mild, moderate, and severe Alzheimer's disease. It does not stop the disease from progressing, but it can ease symptoms for a period.
How donepezil works
Nerve cells in the brain communicate using acetylcholine, and an enzyme called acetylcholinesterase normally breaks it down. In Alzheimer's disease, acetylcholine-producing neurons are lost. Donepezil blocks that enzyme, so more acetylcholine remains available to support the nerve signaling involved in memory and thinking.
Before you take it
- Do not take donepezil if you have had an allergic reaction to it or to similar cholinesterase inhibitors.
- Tell your prescriber about sick sinus syndrome, other heart conduction problems, a history of fainting, asthma or COPD, seizures, or stomach ulcers.
- Combining donepezil with beta-blockers or other heart-rate-lowering drugs increases the risk of a very slow heart rate.
- Tell your surgical team you take donepezil before any operation, since it can prolong the effect of certain muscle relaxants used in anesthesia.
Side effects
Common effects include nausea, diarrhea, loss of appetite, and trouble sleeping, especially when a dose is increased.
Stop and seek urgent medical care for any of these:
- Fainting or a very slow, irregular heartbeat.
- Severe stomach pain, or vomiting blood or material that looks like coffee grounds.
- A seizure.
- Signs of a severe allergic reaction, such as facial swelling or difficulty breathing.
Safety essentials
- Donepezil can slow the heart enough to cause fainting or heart block; anyone with known conduction disease needs a cardiology assessment before starting, and a slow pulse at any point should be checked promptly.
- It increases stomach acid and the risk of ulcers or bleeding, particularly when combined with an NSAID.
- Stopping donepezil abruptly can cause a rapid worsening of symptoms; any change in dose should be planned with your prescriber.
This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.