At a visit to the provider’s office, an older adult client’s…

At a visit to the provider’s office, an older adult client’s partner reports that the client has bradycardia, excessive nausea, diarrhea, and a loss of appetite.  He has a history of Alzheimer’s disease and is taking donepezil (Aricept).  Which medication should the nurse anticipate administering as an antidote to a cholinergic overdose?