Cholinesterase inhibitors

One way Alzheimer's disease harms the brain is by decreasing levels of a chemical messenger (acetylcholine) that's important for alertness, memory, thought and judgment. Cholinesterase (ko-lin-ES-tur-ays) inhibitors boost the amount of acetylcholine available to nerve cells by preventing its breakdown in the brain.

Cholinesterase inhibitors can't reverse Alzheimer's disease or stop the destruction of nerve cells. These medications eventually lose effectiveness because dwindling brain cells produce less acetylcholine as the disease progresses.

Common side effects can include nausea, vomiting and diarrhea. Starting treatment at a low dose and working up to a higher dose can help reduce side effects. Taking these medications with food also might help minimize side effects.

People with certain types of cardiac arrhythmias shouldn't take cholinesterase inhibitors.

Three cholinesterase inhibitors are commonly prescribed:

• Donepezil (Aricept) is approved to treat all stages of the disease. It's taken once a day as a pill.
• Galantamine (Razadyne) is approved to treat mild to moderate Alzheimer's. It's taken as a pill once a day or as an extended release capsule twice a day.
• Rivastigmine (Exelon) is approved for mild to moderate Alzheimer's disease. It's taken as a pill. A skin patch is available that can also be used to treat severe Alzheimer's disease.