Tasmar (tolcapone) has been approved as a treatment of Parkinson's disease, to be taken in combination with levodopa/carbidopa therapy. It is the first of a new class of Parkinson's disease drugs called COMT inhibitors.
Tasmar was shown to significantly improve a patient's ability to function and perform basic daily activities when taken in combination with levodopa/carbidopa. Clinical studies found that advanced Parkinson's disease patients gained a daily average of 1.7-2.9 hours of "on time," periods of relatively good functioning.
The most common reported side effects included dyskinesias (involuntary movements), nausea, sleep disorders, dystonia, anorexia, diarrhea, somnolence, excessive dreaming, muscle cramps, orthostatic complaints/syncope, dizziness, headache, hallucination and confusion.
Although the precise mechanism of action is unknown, it is believed that COMT (catechol-O-methyltransferase) inhibitors work to enhance the effectiveness of levodopa by blocking one of the main enzymes responsible for breaking down levodopa in the bloodstream, before it reaches the brain. By inhibiting the action of the COMT enzyme, Tasmar provides a smoother and more sustained level of levodopa to the brain.