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Systematic (IUPAC) name
2-dihydroxyamino-4- (4-methylbenzoyl)- cyclohexa-2,4-diene-1,6-dione
CAS number 134308-13-7
ATC code N04BX01
PubChem 4659569
DrugBank APRD00445
Chemical data
Formula C14H11NO5 
Mol. mass 273.241 g/mol
Pharmacokinetic data
Bioavailability 65%
Protein binding >99.9%
Metabolism  ?
Half life 2-3.5 hours
Excretion  ?
Therapeutic considerations
Pregnancy cat.


Legal status


Routes Oral

Tolcapone is a drug that inhibits the enzyme catechol-O-methyl transferase (COMT). It is used in the treatment of Parkinson's disease as an adjunct to levodopa/carbidopa medication. It is a yellow, odorless, non-hygroscopic, crystalline compound with a relative molecular mass of 273.25. The chemical name of tolcapone is 3,4-dihydroxy-4’-methyl-5-nitrobenzophenone. Its empirical formula is C14H11NO5.

Tolcapone has the ability to cross the blood-brain barrier and thus exerts its COMT inhibitory effects in the CNS as well as in the periphery.

Tolcapone has demonstrated significant hepatotoxicity that limits the drug's therapeutic utility to a drug of last resort. Entacapone, another COMT inhibitor, is a more popular selection for L-DOPA adjunct therapy in the treatment of Parkinson's Disease because it has a better side effect and toxicity profile.

Normally, administration of levodopa is compromised when COMT converts it to methyldopa. By preventing this effect, more of the levodopa that is administered reaches the CNS. Additionally, levodopa that is in the CNS, after being converted to dopamine, will not be degraded by COMT when tolcapone inhibits COMT activity.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Tolcapone". A list of authors is available in Wikipedia.
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