Donepezil treatments have been reported to last for several years in some patients, with documented persistence on therapy extending up to five years or more. While the typical clinical use of donepezil is for symptomatic management of Alzheimer’s disease and other dementias, some patients continue treatment for long durations, sometimes exceeding half a decade.
Donepezil is a cholinesterase inhibitor that works by increasing acetylcholine levels in the brain, which can help improve cognition and daily functioning in people with mild to moderate Alzheimer’s disease. The drug has a relatively long elimination half-life of about 70 hours in older adults, which supports once-daily dosing and steady therapeutic levels.
Regarding the longest reported durations of donepezil treatment, observational data from real-world clinical practice indicate that persistence rates decline over time but a notable minority of patients remain on donepezil for extended periods. For example, studies tracking medication adherence show that approximately 17-22% of patients are still taking donepezil five years after starting therapy, depending on how discontinuation is defined. This suggests that some patients tolerate and potentially benefit from donepezil for multiple years, with treatment durations of five years or longer documented in clinical settings.
The persistence on donepezil therapy tends to increase with patient age, with older patients (e.g., those over 90) showing higher rates of continued use at five years compared to younger patients. This may reflect differences in disease progression, tolerability, or clinical decision-making. However, overall, donepezil persistence rates are lower than some other antidementia drugs, indicating that many patients discontinue or switch treatments within a few years.
Long-term donepezil use is generally considered safe, with a tolerability profile that allows many patients to remain on the drug for years. The drug’s metabolism primarily involves liver enzymes CYP2D6 and CYP3A4, and it has a low risk of hepatotoxicity compared to older cholinesterase inhibitors. The clinical benefits of donepezil, such as modest improvements in cognition and function, may persist as long as the drug is taken, but the degree of benefit can vary widely among individuals.
In clinical trials, donepezil treatment durations are often shorter, typically ranging from a few months to a year or two, but real-world data provide evidence of longer-term use. Some patients may continue donepezil therapy indefinitely as part of comprehensive dementia care, especially if they experience stabilization or slowing of symptom progression.
In summary, while donepezil is commonly prescribed for mild to moderate Alzheimer’s disease with typical treatment durations of months to a few years, there are documented cases and population data showing treatment persistence for five years or longer. This long-term use reflects both the chronic nature of dementia and the ongoing need to manage symptoms over extended periods.
