Donepezil

What is donepezil (Aricept)?

Donepezil is a drug prescribed by doctors to help treat dementia related to Alzheimer’s disease.

It is only available with a prescription.

The drug belongs to the class of medications known as cholinesterase inhibitors.

Donepezil is a generic medication. Aricept and Aricept ODT are the brand versions of donepezil.

As a cholinesterase inhibitor, donepezil prevents the breakdown of the substance acetylcholine. Acetylcholine helps transmit signals in the brain’s nerves that are vital for learning and memory.

This generic drug is available in the following forms:¹

• Oral tablet (5mg, 10mg, and 23mg)

• Orally disintegrating tablet (ODT) (5mg or 10mg)

What is donepezil used to treat?

Doctors prescribe donepezil to people with Alzheimer’s disease. Symptoms of Alzheimer’s disease include difficulty with:

• Memory

• Learning, language, reading, writing, and cognitive abilities

• Organizing thoughts

• Logical thinking and reasoning

• Coping or adapting to situations

Alzheimer’s disease could significantly change how you live or conduct your daily life.

Donepezil can help you manage these changes and challenges, making day-to-day life easier. It does so by improving your mental functions, such as memory, the ability to think clearly, and interaction with others.

The drug can also slow the progression of Alzheimer’s-related difficulties.

How do you take donepezil?

For mild to moderate Alzheimer’s disease:

• Initial dose of 5mg, taken by mouth, daily, before bedtime

• Dosage can be slowly increased to 10mg daily over four to six weeks

For moderate to severe Alzheimer’s disease:

• Initial dose of 5mg, taken by mouth, daily, before bedtime

• Dosage can be slowly increased to 10mg daily over four to six weeks

• Your doctor can prescribe up to 23mg daily after three months of a 10mg daily dose

Take donepezil with or without food.

To take the orally disintegrating tablet, place it on your tongue and let it dissolve. Once it has dissolved, drink a glass of water. Don’t swallow the tablet whole.

Seeing results

In clinical trials, donepezil’s effectiveness in improving cognitive abilities in people with Alzheimer’s has been studied after one month. You need to give the medication time to raise levels of acetylcholine in your brain, so noticing immediate improvements is unlikely.

You may notice improvements before you have taken donepezil for three months.¹

Potential side effects of donepezil

Most donepezil side effects are mild and might go away when your body gets used to the drug.

About 10% of patients taking donepezil experience symptoms such as nausea, diarrhea, and headaches.¹

Other common side effects include:²

• Vomiting

• Loss of appetite

• Trouble sleeping

• Feeling tired

• Muscle pain

If you experience one of these common side effects and it worsens or continues, speaks to your doctor.

Donepezil can also cause the following serious side effects:²

• Slow heartbeat

• New or worsening nausea, vomiting, heartburn, or stomach pain

• Seizures

• Feeling lightheaded and faint

• New or worsening breathing problems

• Difficulty or pain when urinating

• Bloody or tarry stools

• Coughing up blood or blood in your vomit (may look like coffee grounds)

You must seek urgent medical attention if you develop any serious side effects of donepezil.

Donepezil can also cause an allergic reaction (see below).

Long-term use of donepezil

Your doctor will monitor you to see how donepezil affects you.

The effects may wear off around six to twelve months after you start taking the drug.³ However, don’t stop taking it if you notice a change in your symptoms as doing so could worsen them. Instead, speak to your doctor.

Missed doses

Take your missed dose as soon as you remember. If it’s nearly time to take your next dose, skip the missed dose and resume your normal dosing schedule. Don’t take two doses of donepezil at once as this could have harmful effects.

Continuously missing your dose of donepezil could cause your symptoms to relapse or worsen. Speak to your doctor if you have missed donepezil for a week.

Overdoses

 If you overdose on donepezil, you might experience the following symptoms:

• Severe or extreme nausea

• Vomiting

• Lightheadedness

• Seizures

• Fainting or losing consciousness

• Blurred vision

• Muscle weakness

• Slow heart rate

• Sweating

• Drooling

If you think you or someone else has taken too much donepezil, seek emergency medical care immediately.

Allergy information

Donepezil can cause a severe allergic reaction, but this is rare.

Symptoms of a severe allergic reaction include:

• Trouble breathing

• Swollen throat, mouth, or tongue

• Swollen eyelids, lips, hands, or feet

If you experience these symptoms after taking donepezil, seek medical help or go to the nearest emergency room immediately.

What to discuss with your doctor before taking donepezil

Here are some of the things you need to discuss with your doctor before taking donepezil:

• Any medications you are currently taking — prescription or over-the-counter

• Any vitamins or supplements you are currently taking or plan to start taking during donepezil treatment

• Any allergies you have to specific medications, particularly donepezil

• Any other health conditions, particularly stomach ulcers or bleeding, asthma, irregular heartbeat, problems urinating, or kidney, lung, or heart disease

• Pregnancy: tell your doctor if you are pregnant or planning a pregnancy

• Breastfeeding

• Upcoming surgery, including dental surgery

• Your weight, particularly if you weigh less than 120lb (55kg)

Stopping donepezil

Suddenly stopping donepezil could harm your health. The medication’s positive effects may reverse and symptoms may worsen.

Your doctor might give a tapering dose if you need to stop taking donepezil. This tapering dose will manage your withdrawal effectively. It will allow you to avoid adverse effects and withdrawal symptoms, such as intense hallucinations.

Donepezil and pregnancy

Donepezil is an FDA pregnancy category C drug.⁴ Animal reproduction studies have shown there could be harmful effects on the fetus, but there are no well-controlled, adequate studies in humans.

Ask your doctor if the benefits outweigh the potential risks of taking donepezil during pregnancy.

Donepezil and breastfeeding

Researchers don’t know if donepezil passes to a baby through breast milk. The risks are unknown. Speak to your doctor about the safety of taking donepezil while breastfeeding.

Interactions with other drugs

Some drugs interact with donepezil, so you must tell your doctor about any drugs you are taking to ensure you don’t experience harmful effects.

Donepezil is known to interact with the following drugs:

• Steroids like dexamethasone (Decadron, Dexamethasone Intensol, or Dexpak Taperpak).⁵

• Drugs for heart conditions, like digoxin (Digitek, Cardoxin, or Lanoxin), amiodarone (Cordarone or Pacerone), verapamil (Verelan, Calan, or Covera HS), or atenolol (Tenormin).³

• Antiseizure drugs, like phenytoin (Phenytek or Dilantin) and carbamazepine (Tegretol, Tegretol XR, or Epitol).

• Tuberculosis drugs, like rifampin (Rifadin or Rimactane).

• Antihistamines, like hydroxyzine (Vistaril) and diphenhydramine (Benadryl and others).

• Non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen (Advil or Motrin).

• Bladder medications, like oxybutynin (Ditropan XL), trospium (Sanctura), and darifenacin (Enablex).

• Antidepressants, like bupropion (Aplenzin, Wellbutrin, and others), doxepin, and nortriptyline (Aventyl or Pamelor).

• Drugs to treat multiple sclerosis (MS), including siponimod (Mayzent), ponesimod (Ponvory), and ozanimod (Ziposia). These drugs are sphingosine l-phosphate receptor modulators.⁶

Drug approval history

1996: The FDA approves donepezil (Aricept) as an oral tablet (5mg, 10mg).

2004: The FDA approves donepezil (Aricept) as an orally disintegrating tablet (5mg, 10mg) and oral solution (5mg/5ml).

2010: The FDA approves a new 23mg format of donepezil (Aricept) oral tablets.²

2022: The FDA approves a new dosage form — donepezil (Adlarity) transdermal patches (5mg, 10mg). This is yet to be released.⁷

Tips and advice for taking donepezil

Follow these tips to help you take donepezil safely and get the best results:

• Always take donepezil before you go to sleep.

• Donepezil can slow your heartbeat. Take extra care when getting out of bed to avoid falls and fainting.

• The medication can be taken with or without food. Take it with food to reduce stomach irritation.

• Don’t swallow the orally disintegrating tablet whole. Place it on your tongue and let it melt gradually. Drink a full glass of water after it dissolves.

• Be constantly aware of contraindications with other drugs. Ask your doctor about how to take other drugs together with donepezil. Don’t start taking a new drug, herbal medicine, or supplement without seeking medical advice first.