Urinary incontinence may be a side effect of donepezil, according to researchers from Japan. Of 94 patients with Alzheimer's disease treated with donepezil, 7 per cent developed urinary incontinence, say Dr Mamoru Hashimoto and colleagues (Hyogo institute for ageing brain and cognitive disorders, Himeji). Patients were treated with 3mg a day for one to two weeks followed by 5mg a day thereafter. In the majority of patients, incontinence appeared at the higher dose and was transient.
The researchers comment that urinary incontinence has not been previously reported as an adverse effect of donepezil in clinical trials or in product information. They suggest using a lower dose of donepezil or concomitant use of a peripherally acting cholinergic antagonist (Lancet 2000;356:568).
A spokeswoman for Pfizer, the manufacturer of donepezil (Aricept), told The Journal on August 16 that the urinary incontinence observed might not necessarily be caused by the drug but could be a manifestation of Alzheimer's disease.