Aricept (Donepezil) 5 mg, 10 mg and 23 mg Tablets: Prescription Acetylcholinesterase Inhibitor for Mild-to-Severe Alzheimer’s Dementia

Information last reviewed: May 2026 — for educational purposes only.

Aricept (donepezil hydrochloride) is a prescription acetylcholinesterase inhibitor (AChEI) and the world's most widely prescribed medication for Alzheimer's disease. It works by reversibly inhibiting the enzyme acetylcholinesterase (AChE), which breaks down the neurotransmitter acetylcholine in the brain. In Alzheimer's disease, cholinergic neurons in the basal forebrain progressively degenerate, leading to reduced acetylcholine and impaired transmission in circuits critical for memory and learning. By inhibiting AChE, donepezil increases the availability of acetylcholine at synapses — partially compensating for the cholinergic deficit and improving cognitive and functional symptoms. It does not halt or reverse the underlying neurodegeneration.

Donepezil is FDA-approved for all stages of Alzheimer's disease: mild, moderate, and severe. It is the only AChEI approved for severe Alzheimer's (the 23 mg tablet form is specifically indicated for moderate-to-severe disease after stabilisation on 10 mg). It is also used off-label for dementia associated with Parkinson's disease and other dementia syndromes (though rivastigmine has a specific approval for Parkinson's dementia). Once-daily dosing at bedtime improves adherence and places peak cholinergic effects during sleep, while positioning side effects (nausea, vivid dreams) when the patient is asleep rather than active.

What Is Donepezil?

Donepezil is a selective, reversible AChE inhibitor. Unlike rivastigmine, it does not inhibit butyrylcholinesterase (BuChE), and unlike tacrine (the first AChEI, now withdrawn due to hepatotoxicity), it has no liver toxicity concerns. Its very long half-life (~70 hours) allows for once-daily dosing and produces stable plasma concentrations — a significant pharmacokinetic advantage. Common side effects are cholinergic: nausea, diarrhoea, insomnia, and vivid dreams at initiation or dose escalation; bradycardia in susceptible patients (cholinergic cardiac effect). The 5 mg starting dose for 4–6 weeks before escalating to 10 mg allows GI tolerance to develop. The 23 mg dose is associated with more side effects and is appropriate only for moderate-severe disease after the patient is well-established on 10 mg.

Prescription Status

Donepezil is prescription-only in the United States. All doses (5 mg, 10 mg, 23 mg) require a physician prescription. Prescribing for Alzheimer's typically involves a neurologist, geriatrician, or psychiatrist experienced in dementia management, though primary care physicians can also prescribe.

Strengths and Available Forms

• 5 mg standard tablets — initial dose; taken at bedtime once daily for first 4–6 weeks; allows GI tolerance to develop before dose escalation
• 10 mg standard tablets — most common maintenance dose; good evidence for mild-to-moderate Alzheimer's across all major trials
• 5 mg and 10 mg orally disintegrating tablets (ODT) — dissolve on tongue without water; useful for patients with dysphagia or who resist pill-taking; identical bioavailability to standard tablets
• 23 mg tablets (extended-release matrix) — indicated for moderate-to-severe Alzheimer's in patients already on 10 mg for ≥3 months; higher dose provides additional but modest (approximately 2 ADAS-cog point) benefit in moderate-severe disease; more GI and neurological side effects than 10 mg; NOT a simple 10 mg dose increase — it is a different tablet formulation with different dissolution kinetics

Donepezil is taken as a single bedtime dose. This timing positions peak plasma levels (and thus peak cholinergic activation) during sleep, reducing daytime cholinergic side effects. Nausea and vivid/abnormal dreams are common at dose initiation and escalation — typically transient and manageable for most patients.

Price of Aricept / Generic Donepezil

Generic donepezil 5 mg and 10 mg tablets and ODTs are available at very low cost at US pharmacies and are on most $4 generic formularies. The 23 mg form is more expensive (generic available but higher cost than lower strengths). Brand-name Aricept is considerably more expensive. Insurance covers generic donepezil universally.

Frequently Asked Questions

How much cognitive improvement should be expected from donepezil?

The benefit of donepezil and other AChEIs in Alzheimer's disease is real but modest in statistical terms — typically 1.5–3 points on the 70-point ADAS-cog scale. More clinically meaningful is that treated patients often maintain functional abilities for longer (dressing, meal preparation, self-care), and the rate of functional decline is slowed. Benefits on cognition, global function, and activities of daily living are consistently demonstrated across multiple randomised controlled trials. Many families also report that the patient seems "more like themselves" — more engaged, better social responsiveness — particularly in milder disease stages. Donepezil does not work for everyone and does not stop disease progression, but it provides clinically meaningful benefit for a substantial proportion of patients.

Does donepezil still work in severe Alzheimer's?

Yes — donepezil (and specifically the 23 mg formulation) has demonstrated benefit in severe Alzheimer's disease in clinical trials. The DOMINO-AD trial and others confirmed that continuing donepezil in moderate-severe disease produces better cognitive and functional outcomes than withdrawing it. Many patients worsened significantly when donepezil was discontinued. In severe disease, donepezil can be combined with memantine (an NMDA antagonist) — the combination is more effective than either alone in moderate-severe disease according to multiple trials, and this combination therapy is standard practice at specialist dementia centres for this stage.

When should donepezil be discontinued?

Donepezil should generally be continued throughout Alzheimer's disease unless it is causing intolerable side effects, the patient can no longer benefit (very end-stage disease with no meaningful wakefulness), or the patient or their family elects to discontinue as part of comfort care planning. Abrupt cessation of donepezil has been associated with rapid functional decline in some patients, suggesting ongoing benefit even in advanced disease. Stopping donepezil should involve a thoughtful discussion between the prescribing physician, patient (if able), and family or caregivers about the goals of care at that stage of illness.

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