Adverse effects talcapone entacapone

Both drugs exhibit adverse effects that are observed in patients taking levodopa–carbidopa, including diarrhea, postural hypotension, nausea, anorexia, dyskinesias, hallucinations, and sleep disorders. Most seriously, fulminating hepatic necrosis is associated with tolcapone use. Therefore, it should be used, along with appropriate hepatic function monitoring, only in patients in whom other modalities have failed. Entacapone does not exhibit this toxicity and has largely replaced tolcapone.