is FDA indicated as adjunctive therapy to treat patients with Parkinson disease who 
are currently on levodopa/carbidopa( Fig 1.5 ). Only patients who are experiencing 
motor fluctuations or who cannot tolerate other therapies should use tolcapone. 
Research shows that a majority of patients with Parkinson disease who have received 
treatment with levodopa and carbidopa experience a "wearing-off" phenomenon. 
During this "wearing-off" phenomenon, patients experience shortened periods of 
benefit from their levodopa/carbidopa , tolcapone and other therapy. Patients 
experience a so-called "off" time where they do not experience any therapeutic benefit 
of their medication; this usually requires an increase in dosage or more frequent 
dosing of levodopa so that patients experience more "on" time of therapeutic benefit 
from levodopa.[22]
Studies show that patients with Parkinson disease who are currently experiencing 
motor fluctuations while taking levodopa and carbidopa showed reduced "off" time 
and increased "on" time when adding tolcapone to their medication regimen compared 
to placebo. These studies also showed that patients were able to tolerate a dose 
reduction of their levodopa. However, if patients do not show improvement on 
tolcapone within three weeks of initiation, tolcapone should be discontinued.[23][24]
There are no off-labeled uses for tolcapone. However, researchers have studied the use 
of tolcapone in patients with Parkinson's disease who are stable on 
levodopa/carbidopa. Researchers found that when they added tolcapone to 
levodopa/carbidopa, patients saw improvement in scores for activities of daily living 
and motor function on the Unified Parkinson's Disease Rating Scale. The groups 
receiving tolcapone also saw a decrease in their total daily dose of levodopa.[25]