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Donepezil is an acetylcholinesterase inhibitor.

The introduction of Acetylcholinesterase inhibitors (AChEI) in 1997 had a great impact in the management of Alzheimer’s disease (AD), (Birks, 2006). AChEI are usually considered first line pharmacotherapy for mild-moderate AD and donepezil is often the first drug of choice, due to its cost effectiveness.

Mechanism of Action

  • Reversible and a non-competitive inhibitor of Acetylcholinesterase (AChE)
  • Prevents the breakdown of acetylcholine (Ach), (Ach degraded down to acetate and choline by AChE) within the synapses of the brain
  • Increasing the Ach concentration within the brain

Cholinergic Hypothesis- States that AD is caused by a reduction of the neurotransmitter Ach.

Indications and dose

Mild-moderate AD

  • Oral administration
  • Initially 5mg OD
  • Increase dose to 10mg OD if necessary
  • Doses should be given at bedtime


  • Asthma, COPD
  • Sick sinus syndrome
  • Supraventricular conduction abnormalities
  • Patients who are susceptible to peptic ulcers

Side effects

Common or very common

Abnormal dreams, aggression, agitation, anorexia, diarrhoea, dizziness, fatigue, hallucinations, headache, insomnia, muscle cramp, nausea, pruritus, rash, syncope, urinary incontinence, vomiting. (BNF, 2015)

Side effects, further information

AChEI can cause unwanted cholinergic effects and therefore should be started at the lowest dose possible. The dose should be increased according to the patient’s response and tolerability.

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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