By Vimal Aga, MD, Board-certified Geriatric psychiatrist and Assistant Professor of Psychiatry,
Oregon Health Sciences University, Portland, OR
The acetylcholinesterase inhibitors, also called cholinesterase inhibitors include donepezil (Aricept), rivastigmine (Exelon), and galantamine (Razadyne). They are used for the treatment of major neurocognitive disorder (dementia) due to Alzheimer’s disease and other causes.
*How to choose between them*
It is important to note that none of the cholinesterase inhibitors works better than the others. There are some differences in the pharmacological effects of the different cholinesterase inhibitors, but these are not of clinical importance.
2. Adverse effects?
Rivastigmine appears to have more adverse effects than donepezil (Birks, 2006). There is also observational data to suggest that long-term adherence may be worst with rivastigmine and best with galantamine (Fisher et al., 2017). Based on this, we recommend not using rivastigmine as the first choice of a cholinesterase inhibitor.
3. Dementia type?
In dementia with Lewy bodies, it is believed that donepezil may exacerbate carotid sinus hypersensitivity more so than the other cholinesterase inhibitors. Pending further research, it is recommended that galantamine and rivastigmine be preferred over donepezil in patients who have dementia with Lewy bodies.
Donepezil is significantly cheaper than the others–about $17 per month versus about $70 per month.
Is it important to have once-a-day versus twice-a-day dosing?
Donepezil and memantine are taken once a day, which is more convenient. Galantamine and rivastigmine are taken twice a day. Of these, galantamine is also available as an extended-release, once a day preparation (Razadyne ER) but as of April 2017, it is available as brand name only.
6. Gastrointestinal adverse effects?
If a person has nausea, vomiting, etc, which are common adverse effects of cholinesterase inhibitors, using a transdermal patch can be helpful. The only cholinesterase inhibitor that comes as a transdermal patch (as of April 2017) is rivastigmine (Exelon-TD).
7. Renal or hepatic disease?
Of the three cholinesterase inhibitors, only galantamine requires the dose to be limited if moderate renal or hepatic impairment is present and for the medication to be avoided if severe renal or hepatic impairment is present. Therefore, we may prefer the other medications in cases of significant hepatic or renal impairment