Tm5 38:57 nau TOL CAPONE Tasmar Pharmacology. Tolcapone reversibly inhibits at least 80% of the activity of CONT. This action prevents the metabolism of levodopa to 3-0-methyldopa and thus prolongs its duration of action, especially with co-administration of car bidopa 333,334 Tolcapone increases plasma levodopa bioavailability by about 2-fold and variably prolongs te terminal half-life of levodopa (given with carbidopa) the elderly from 2 hr to as long as 3.5 hr, but has no effect on the peak serum lev els of levodopa or the time at which they occur. (See Notes.) Administration and Adult Dosage. Po for Parkinson's disease 100 mg tid ini tially, always as an adjunct to levodopalcarbidopa therapy. increasing to a maxi