[Interaction of donepezil and muscular blockers in Alzheimer's disease].

A 75-years-old man with Alzheimer's disease, treated with the cholinesterase inhibitor donepezil for 14 months, was scheduled for left colectomy under general anesthesia. During the procedure, succinylcholine-induced relaxation was prolonged and the effect of atracurium besylate was inadequate even at higher doses than those indicated for the patient's weight. Cholinesterase blood tests performed 10 months, 1 month and 10 days before surgery had demonstrated a gradual decrease in the duration of activity of the enzyme. Such an effect, which has been described for cholinesterase inhibitors like neostigmine and donepezil, would explain the prolonged effect of succinylcholine. After ruling out other causes for resistance to atracurium, we conclude that donepezil or its metabolites acted on muscle plaque, blocking acetylcholine hydrolysis and antagonizing atracurium.