What Is Donepezil (Aricept)?

Reviewed by: HU Medical Review Board | Last reviewed: June 2022 | Last updated: January 2023

Several kinds of drugs are approved to treat the cognitive symptoms of Alzheimer’s disease, including some drugs that are cholinesterase inhibitors. Cholinesterase inhibitors help to prevent the breakdown of acetylcholine, which is a neurotransmitter involved in learning and memory.1 By preventing the breakdown of the chemical, communication between nerve cells in the brain may be improved. This can lead to a slowing down of symptoms or a delay in exhibiting symptoms.

One of these inhibitors is donepezil, brand name Aricept. This drug was approved for all stages of Alzheimer’s disease and is probably one of the better-known drugs for the condition. While this drug (and others) help address symptoms of Alzheimer’s, they do not treat the underlying disease or stop the progression of the disease.

What is the ingredient in donepezil?

Donepezil hydrochloride is the active ingredient in Aricept, and is a reversible inhibitor of acetylcholinesterase.2

How does donepezil work?

In the brain, there are chemicals called neurotransmitters. Neurotransmitters help transmit communication between cells and can help with cognition, mood, and memory. Enzymes breakdown neurotransmitters to maintain the correct amount of these chemicals in the brain, and donepezil works on one of these enzymes called acetylcholinesterase.

Acetylcholinesterase breaks down the neurotransmitter acetylcholine. Donepezil inhibits acetylcholinesterase to keep it from breaking down acetylcholine, thereby increasing acetylcholine levels in the brain, encouraging more communication between nerve cells and potentially improving memory and cognition.3

What are the possible side effects of donepezil?

Any medication has possible adverse effects, and it’s important to be aware of the potential side effects when a patient starts a drug.

The most common side effects of donepezil include:2

  • nausea
  • diarrhea
  • insomnia
  • loss of appetite
  • muscle cramps
  • fatigue
  • vomiting

These side effects resolved over time during the clinical trials, and patients did not need to reduce their dosage or stop the drug because of these side effects.

Other possible side effects that have been noted include discoloration of the skin, hallucinations, eczema, depression, headache, high blood pressure, fever, nervousness, chest pain, confusion, dizziness, mood swings, sleepiness, and urinary issues.2

These are not all the possible side effects of donepezil. Patients should talk to their doctor about what to expect with treatment with donepezil.

If a patient starts taking donepezil and notices any abnormal symptoms or side effects, tell the doctor immediately so these can be monitored. Often the mild side effects will resolve over time, but more serious side effects may warrant a dosage change or change of drug. Gastrointestinal side effects are the most common reason patients discontinue donepezil, the chances of these side effects can be decreased by gradually increasing the dose.

Things to know about donepezil

If a patient has any heart conditions, they should tell their doctor. Donepezil may cause fainting in those with cardiac conditions.2 Because this drug also increases gastric acid secretion, patients taking this medication should be monitored for GI bleeding, especially those with ulcer disease.2 If a patient has asthma or a pulmonary condition, this may not be an appropriate medication for that person, so talk with the doctor about the potential effects of the drug on breathing.

Donepezil should be taken in the evening, before bed, and can be taken with or without food.

For more information, read the full prescribing information of donepezil.

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