Saturday, August 27, 2011

Aricept (Donepezil) – Number One Prescription Drug against Alzheimer’s Disease

About Aricept (Donepezil)

Aricept, which is claimed to be the #1 prescription drug against Alzheimer’s disease in the USA these days, belongs to the class of chemical substances, called cholinesterase inhibitors. It could be thrilling to note, that during World War II the representatives of this very group of chemicals were mainly developed for warfare purposes: such terrifying and deadly weapons as neuroparalytic gases sarin, soman, and VX also belong to the class of cholinesterase inhibitors.

Happily, nowadays the properties of cholinesterase inhibitors are used mainly for peaceful purposes; one of them is to help people conquer Alzheimer’s disease - one of the most devastating mental illnesses of elderly people.

Today there are three substances of cholinesterase inhibitors group, which are approved for medicinal use – donepezil, galantamine and rivastigmine. However, it is only donepezil or Aricept as the brand medication, which is approved for the use in patients on all stages of Alzheimer’s disease (others are used only for mild to moderate conditions). Donepezil is said to be the most potent among other representatives of cholinesterase inhibitors.

Aricept was developed by Eisai Inc. and approved by the FDA in 1996. It is currently co-promoted by Eisai Inc. and Pfizer Inc.

There is a preliminary research data claiming that combination Aricept and memantine, another anti-Alzheimer’s medication, may significantly increase the effectiveness of the treatment.

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Aricept as Alzheimer’s Treatment

As was mentioned earlier, Aricept is part of a group of drugs called acetycholinesterase inhibitors used to treat mild to moderate cognitive symptoms of Alzheimer’s. There is no clinical evidence that it can actually alter the course of the disease or help repair damaged brain cells.

It is believed that the chemical acetylcholine, which transmits messages between brain cells in the area responsible for memory and acquiring new information, is reduced in the brains of people with Alzheimer’s disease.

Acetycholinesterase inhibitors, such as Aricept, help prevent the breakdown of this important chemical, therefore helping to delay deterioration. In some cases it has delayed symptoms by around 12 months.

In one study where some people received Aricept and others received a placebo, those who took the drug were twice as likely to show some improvement in thinking and understanding. For many it delayed their decline for up to 12 months.

For some people the drug doesn’t have any effect at all or, if it does, their condition stays the same when it could have been expected to deteriorate.

And it doesn’t have any effect in the later stages of Alzheimer’s because there are so few acetylcholine-producing cells left.

The drug is only available in prescription form and it’s up to a doctor to decide whether it’s suitable for the individual Alzheimer’s sufferer.

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Aricept is available in tablet form or an orally disintegrating tablet form, and is commonly started at 5 mg a day. If it's well tolerated after 4 to 6 weeks, the dosage may be increased to 10 mg a day.

Aricept has been approved by the FDA in dosages of 5 to 10 milligrams for patients with mild to moderate cases of Alzheimer's and in a dose of 10 to 23 milligrams for more severe cases. There are ongoing efforts requesting FDA to ban the 23-mg version of the drug and to warn patients and physicians against taking two 10-mg. pills per day if the higher dosage is removed from the market.

Clinical trials of Aricept submitted to the FDA for approval show no significant benefit from the 23-mg version compared to the 10-mg version. But the increased adverse effects from the higher dosage include a slowed pulse rate, nausea, vomiting, diarrhea, urinary incontinence, fatigue, dizziness, agitation, confusion and anorexia. Vomiting, which occurred more than 3 1/2 times more frequently in those taking the high dosage, is a particularly dangerous side effect for Alzheimer's patients, because it can lead to pneumonia, massive gastrointestinal bleeding, esophageal rupture and even death.

"With no evidence of an added advantage in benefit to patients, the clear increase in risk should have been more than adequate grounds for denying approval," said Dr. Sidney Wolfe, director of Public Citizen's Health Research Group. "It is inexcusable that FDA approved this higher dose. Its prompt removal would belatedly fulfill the agency's mission to allow only drugs whose benefits outweigh their risks to be marketed."

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Side Effects

While applied to the normal doses of the drug, side effects of the drug are generally well-tolerated. Nausea, vomiting, diarrhea, loss of appetite/weight loss, dizziness, drowsiness, weakness, trouble sleeping, shakiness (tremor), or muscle cramps may occur as your body adjusts to the drug. These effects usually last 1-3 weeks and then lessen. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects.

Many people using this medication do not have serious side effects. Tell your doctor right away if any of these serious side effects occur: slow/irregular heartbeat, fainting, trouble urinating, severe stomach/abdominal pain, black stools, vomit that looks like coffee grounds, seizures. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

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Potential Interactions

Drugs with anti-cholinergic properties that can cross into the brain, such as atropine, benztropine (Cogentin), and trihexyphenidyl (Artane) counteract the effects of donepezil and should be avoided during therapy with donepezil.

Donepezil is metabolized (eliminated) by enzymes in the liver. The rate of metabolism of donepezil may be increased by medications that increase the amounts of these enzymes, such as carbamazepine (Tegretol), dexamethasone (Decadron), phenobarbital, phenytoin (Dilantin), and rifampin (Rifadin). By increasing elimination, these drugs may reduce the effects of donepezil.

Ketoconazole (Nizoral) has been shown to block the enzymes in the liver that metabolize donepezil. Therefore, concurrent use of ketoconazole and donepezil may result in increased concentrations of donepezil in the body and possibly lead to donepezil side effects. Quinidine (Quinidex, Quinaglute) also has been shown to inhibit the enzymes that metabolize donepezil and may cause donepezil side effects.

Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, also should be used with caution while taking Aricept, due to the increased risk of stomach ulcers.

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