Alzheimer's drugs slow progression of disease
Alzheimer's still has no cure, but two different types of drugs have been found to slow the progression of the disease.
Medication can improve the quality of life for people with Alzheimer's and their caregivers. It may even delay placement in a nursing home.
Unfortunately, Alzheimer's medications don't work for everyone. Some of the most commonly used drugs work in less than half the people tested. For those who are helped, the drugs' effects often are modest and temporary. Scientists continue to search for more effective drugs that might someday prevent Alzheimer's.
Two main types of drugs are currently approved by the Food and Drug Administration (FDA) for use in Alzheimer's. One variety seems to work best in the earlier stages of the disease, while the other is typically reserved for treatment of the later stages.
Cholinesterase inhibitors
Alzheimer's disease changes the brain in many ways. One of the changes results in a decrease in the levels of acetylcholine, a chemical messenger that's believed to be important for alertness, memory, thought and judgment. Cholinesterase inhibitors are a type of drug that improves the effectiveness of acetylcholine either by increasing the amount of it in the brain or by enhancing nerve cells' response to it.
Cholinesterase inhibitors work best in the early to middle stages of Alzheimer's, although at least one study has reported improvements in cognition and behavior in people who have moderate to severe Alzheimer's.
In clinical studies, on average, all cholinesterase inhibitors work equally well. But in individuals, one cholinesterase inhibitor may work better or produce fewer side effects than does another. Side effects can include nausea, vomiting and diarrhea.
Types of cholinesterase inhibitors
The most commonly prescribed cholinesterase inhibitors are donepezil (Aricept), galantamine (Razadyne) and rivastigmine (Exelon).
Donepezil (Aricept)
Perhaps the most prescribed cholinesterase inhibitor, donepezil was the first to offer convenient once-a-day dosing and is the least likely to produce serious side effects. This drug also appears to temporarily postpone the development of Alzheimer's in people with mild cognitive impairment (MCI), a memory-related condition that may precede Alzheimer's.
Galantamine (Razadyne)
Originally marketed as Reminyl, galantamine is taken twice a day with food, which can help reduce gastrointestinal side effects. It is also available in an extended release form designed to be taken once a day. Studies involving more than 2,000 people with MCI showed a significantly higher rate of death in those who took galantamine, compared with those receiving placebo. Half the deaths in the galantamine group were associated with heart attacks and strokes.
Rivastigmine (Exelon)
Rivastigmine may cause more severe gastrointestinal problems than other cholinesterase inhibitors do. Doctors typically prescribe a low dose of the drug initially and slowly increase the dosage as the body becomes accustomed to it. Taking the medication with food also may help. Rivastigmine is also now available in an adhesive patch, which may help reduce gastrointestinal side effects.
MORE ON THIS TOPIC
* Donepezil (Oral Route)
http://www.mayoclinic.com/health/drug-information/DR600577
* Galantamine (Oral Route)
http://www.mayoclinic.com/health/drug-information/DR601639
* Rivastigmine (Oral Route)
http://www.mayoclinic.com/health/drug-information/DR601215
Memantine for later stages
Memantine (Namenda) is the first drug to be approved by the FDA for treatment of moderate to severe Alzheimer's disease. It works by regulating the activity of glutamate, a messenger chemical involved in all brain function — including learning and memory. Its most common side effect is dizziness.
People with moderate Alzheimer's may experience even better results by taking memantine along with a cholinesterase inhibitor.
MORE ON THIS TOPIC
* Memantine (Oral Route)
http://www.mayoclinic.com/health/drug-information/DR601519
When to discontinue Alzheimer's drugs
It often is difficult to tell if Alzheimer's drugs are providing any benefit, because no one knows how quickly the disease would have progressed without the medications. If a person experiences a sudden decline in abilities after an Alzheimer's drug is discontinued, it may be best to contact your doctor about restarting the drug.
Until researchers find a cure — or can halt the progression of Alzheimer's — slowing the downward spiral remains the only benefit drugs can offer. But even temporary improvements in memory or thinking ability can help extend the amount of quality time a person with Alzheimer's has with his or her family.
By Mayo Clinic Staff
July 27, 2007
