Donepezil

Benjamin Clanner-Engelshofen is a freelance writer in the medical department. He studied biochemistry and pharmacy in Munich and Cambridge / Boston (USA) and noticed early on that he particularly enjoyed the interface between medicine and science. That is why he went on to study human medicine.

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The active ingredient donepezil is used for the symptomatic treatment of mild to moderate forms of Alzheimer's dementia (forgetfulness). It improves memory and memory, but does not prevent the disease from progressing. Here you can read everything interesting about Donepezil: effect, application and possible side effects.

This is how donepezil works

Donepezil is an anti-dementia drug. The most common form of dementia is Alzheimer's disease. With this, nerve cells (neurons) in the brain gradually die. Usually a not insignificant part of the nerve cells has died before the first symptoms appear and the disease is discovered. Acetylcholine is one of the most important messenger substances (neurotransmitters) between nerve cells that are involved in memory, retentiveness and memory.

To communicate with other neurons, a nerve cell can secrete messenger substances such as acetylcholine. This docks to special docking points in the membrane of the second nerve cell and thus transmits a specific signal. Then the neurotransmitter is split by an enzyme (acetylcholinesterase) into acetate and choline, which no longer act on the receptors, whereby the signal is terminated. The two fission products are taken up again in the first nerve cell, linked and can then be released again if necessary.

Since nerve cells not only have one-to-one connections, but rather a nerve cell is usually in contact with many thousands of other nerve cells, one notices that the cells are dying off only when a threshold value has been exceeded. The remaining cell contacts are then no longer sufficient to transmit signals.

To alleviate the symptoms of Alzheimer's disease and improve memory performance, donepezil is used as a selective inhibitor of the enzyme acetylcholinesterase. When this enzyme is inhibited in the brain, acetylcholine stays longer on the receptors of the downstream nerve cell, which makes the signal stronger, so to speak. This means that the remaining nerve cells can still communicate with normal intensity.

Uptake, breakdown and excretion of donepezil

After ingestion, the active ingredient donepezil reaches the blood via the intestine and from there via the blood-brain barrier to the central nervous system. There it unfolds its effect. In the liver, donepezil is partly metabolized into effective and ineffective breakdown products. Most of these are excreted in the urine and to a lesser extent in the stool. About 70 hours after ingestion, half of the active ingredient left the body.

When is donepezil used?

Donepezil is approved for the symptomatic treatment of mild to moderate Alzheimer's dementia.

Outside of the approval area (“off-label” use) it is also used as a palliative drug in severe Alzheimer's dementia.

It has to be taken permanently in order to maintain the effect.

This is how donepezil is used

The active ingredient is taken as salt (donepezil hydrochloride) in the form of tablets or orodispersible tablets that dissolve in the mouth in seconds. Treatment is started with five milligrams of donepezil once a day. After a month, the doctor will assess whether the dosage is sufficient or whether it should be increased to ten milligrams of donepezil daily. Higher dosages are not recommended.Therapy should only be given if the patient is housed in a care facility or has a caregiver who monitors the use of donepezil.

What are the side effects of donepezil?

More than ten percent of those treated complain of diarrhea, nausea and headaches.

Often while taking donepezil, there is also loss of appetite, aggressive behavior, agitation, dizziness, insomnia, vomiting, indigestion, rashes, muscle cramps, incontinence and tiredness.

Donepezil side effects such as seizures, slow heartbeat, and gastrointestinal bleeding may also occur in 1 in 100 to 1,000 people.

What should be considered when taking donepezil?

Since the active ingredient donepezil is mainly broken down in the liver by two different enzymes (cytochrome P450 2D6 and 3A4) that also break down other active ingredients, there may be interactions when these active ingredients are combined.

Examples include many antibiotics (erythromycin, metronidazole, chloramphenicol), HIV drugs (ritonavir, indinavir), the blood pressure drug verapamil, anti-fungal agents (fluconazole, ketoconazole, itraconazole) and also many herbal remedies (valerian, turmeric and grapefruit) .

Some active ingredients ensure that more enzymes are produced in the liver, which then break down donepezil more quickly. Its effectiveness suffers as a result. This is caused, for example, by agents against cramps and epilepsy (phenytoin, carbamazepine, oxcarbazepine), the anesthetic phenobarbital and also some foods (ginger, garlic, licorice).

Patients with respiratory diseases such as asthma or COPD should take donepezil with caution as the risk of an asthma attack may increase.

If non-steroidal anti-inflammatory drugs (NSAIDs such as ASA, ibuprofen, diclofenac) are taken regularly in addition to donepezil, the risk of gastrointestinal bleeding may increase.

Children and adolescents as well as pregnant and breastfeeding women should not take donepezil, as there are no studies on the safety of ingestion and effectiveness.

Likewise, patients with severe hepatic impairment should not take donepezil due to lack of experience.

How to get donepezil medication

The anti-dementive donepezil can be bought from a pharmacy with a doctor's prescription.

Since when is donepezil known?

Development of donepezil began in 1983 at the Japanese pharmaceutical company Eisai. The active ingredient was first approved in the USA in 1996. Generics containing the active ingredient donepezil have been on the market since 2010.

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