Cholinesterase inhibitor efficacy -- brief overview
Medication for Alzheimer's disease
Last updated: Tuesday, December 09, 2008
Currently, three drugs are available that can improve memory and delay disease progression in Alzheimer's disease. The drugs belong to the class called cholinesterase inhibitors (ChE-I) and are represented by donepezil (Aricept), rivastigmine (Exelon), and galantamine (Reminyl).
It is important to see these medications in the correct perspective. The cholinesterase inhibitors are expensive and will cost between R600 and R1 200 per month. Reminyl is the cheapest in South Africa.
These drugs work by inhibiting an enzyme called cholinesterase, thus increasing the concentration of the chemical acetylcholine in the brain. They have two main benefits; they improve memory and improve functioning in daily activities.
However, not everyone will experience the improvement. Most studies indicate that about 40 to 50 % of people experience a 1-5 point improvement on the Mini Mental Status Examination test. Most people will experience a delay in the progression of the illness. Functioning in activities of daily living improves and caregivers will notice this change.
The benefits are more prominent in the early stages of the illness and many scientists say that the benefits in advanced illness are, at most, modest.
The cholinesterase inhibitors are also beneficial in mild cognitive impairment (MCI). In this condition the medication can delay conversion to dementia.
Cholinesterase inhibitors should be prescribed as early as possible in Alzheimer's disease. The medication should be used throughout the illness and may be stopped during advanced stages of the disease. The recommended dose for Reminyl is 8 mg per day, for Aricept 10 mg a day, and for Exelon, the highest tolerable dose, which may be 12 mg a day.
These drugs seem to be equally effective and if an inadequate response is seen on one drug, it may be an indication to switch to another drug. Side effects consist of nausea, vomiting, diarrhoea, gastric upsets, fatigue, dizziness, headache, and increased nasal secretions. Studies have shown that Reminyl and Aricept have fewer side effects than Exelon.
These drugs have changed our thinking about Alzheimer's disease. Most doctors used to be pessimistic about the illness, but now we have something to fight back with and to actually improve symptoms and functioning.
Written by Dr Frans Hugo, MBChB, M.Med Psychiatry and Dr L. Van Wyk, MBChB, M. Med (Psych) from the Panorama Memory Clinic.
For more information visit: Dementia SA: http://www.dementiasa.org/ or Alzheimer’s South Africa: http://www.alzheimers.org.za
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