Despite the clinical advantages of AD therapy,
patients who fail to respond to a particular cholines-
terase inhibitor or who cannot tolerate its adverse
effects, such as gastrointestinal symptoms, may
have to discontinue therapy or switch to another
cholinesterase inhibitor.[14-16] Studies have demon-
strated that patients who discontinued therapy with
donepezil have benefited from switching to rivas-
tigmine.[14-17] About 25–55% of patients who failed
to respond to donepezil therapy were found to re-
spond to rivastigmine therapy, and 30–85% of pa-
tients who discontinued donepezil because of tolera-
bility problems were able to tolerate rivastig- mine.