Report: Donepezil-Induced Myoclonus with Alzheimer's Disease

the MPR take:

Donepezil HCI is currently indicated for Alzheimer's dementia with daily doses ranging from 5mg (mild-to-moderate) to 23mg (moderate-to-severe). The first reported case of drug-induced myoclonus in a patient with Alzheimer’s disease is described in a newly published case report in the journal Annals of Pharmacotherapy. An 80-year-old woman presented with myoclonic jerks in upper and lower extremities with onset two days prior to hospital admission; after 36 hours of donepezil remission, the frequency of myoclonic jerks dramatically decreased. It was determined that the patient was taking 30mg/day of donepezil; after six months on a 10mg/day dose, she remains asymptomatic. Other similar adverse reactions have been reported in patients with Alzheimer’s disease taking memantine, although the exact mechanisms are not fully known. Clinicians should carefully monitor patients with Alzheimer’s disease for potential drug toxicity from donepezil and memantine and use caution in prescribing the maximum daily dose.

Objective: To report an uncommon adverse event in an elderly patient related to the cholinesterase inhibitor, donepezil. Case Summary: An 80-year-old Greek woman with Alzheimer disease was admitted to the hospital with a sudden onset of myoclonus in both upper and lower extremities after receiving 30 mg of donepezil daily for 25 days.