From the FDA Drug Label
- 1 Dosing in Mild to Moderate Alzheimer's Disease The recommended starting dosage of donepezil hydrochloride tablets is 5 mg administered once per day in the evening, just prior to retiring.
- 2 Dosing in Moderate to Severe Alzheimer's Disease The recommended starting dosage of donepezil hydrochloride tablets is 5 mg administered once per day in the evening, just prior to retiring.
- 3 Administration Information Donepezil hydrochloride tablets should be taken in the evening, just prior to retiring.
The reason to take donepezil at night versus the morning is that the drug label explicitly recommends administering the drug in the evening, just prior to retiring 1. This is stated for both mild to moderate and moderate to severe Alzheimer's disease. The exact reason for this recommendation is not provided in the label, but it suggests that taking the drug at this time is the preferred administration schedule.
From the Research
Donepezil is typically recommended to be taken at night rather than in the morning to minimize the impact of its side effects, such as nausea, vomiting, and diarrhea, which may be less bothersome if they occur during sleep. The medication has a long half-life (about 70 hours), so the timing of the dose doesn't significantly affect its effectiveness for treating Alzheimer's disease or other forms of dementia 2. Donepezil works by increasing acetylcholine levels in the brain by inhibiting the enzyme that breaks it down, which helps improve cognitive function. Some patients may experience insomnia with donepezil, but this tends to be less common than the gastrointestinal side effects. If nighttime dosing causes sleep disturbances, morning administration can be considered, but this should be discussed with your healthcare provider.
Key points to consider when taking donepezil include:
- Consistently taking the medication at the same time each day to maintain steady blood levels
- Being aware of potential side effects, such as gastrointestinal symptoms and insomnia
- Discussing any concerns or issues with your healthcare provider to determine the best approach for your individual needs
- Considering the potential for donepezil to cause hypokalemia, a rare but potentially serious side effect, as reported in a recent case study 3.
It's also important to note that donepezil has been shown to be well-tolerated and effective in treating Alzheimer's disease and other forms of dementia, with benefits including delayed nursing-home placement and improvement in cognitive function and global function 4, 2. However, the most recent and highest quality study on this topic is from 2021, which highlights the importance of considering the potential impact of donepezil on gastrointestinal health and myoelectric activity 5.