COMT Inhibitors

Entacapone and tolcapone are used in the treatment of Parkinson's disease. Levodopa is converted to a byproduct peripherally by COMT (catechol-O-methyltransferase). This byproduct competes with levodopa for transport to the CNS.  By inhibiting COMT, less byproduct is produced, and more levodopa is transported to the CNS.

Class Drug

• Entacapone

• Tolcapone

Class Mechanism of Action

Inhibits COMT (Catechol-O-methyltransferase)

• COMT converts levodopa to a byproduct peripherally. The byproduct competes with levodopa for transport to the CNS.

• By limiting byproduct production, more levodopa is transported centrally by active transport.

Class Application

Parkinson's Disease

• Increases transport of levodopa to CNS.

• Reduces the symptoms of levodopa/carbidopa wearing off.

Class Adverse Effects

• Diarrhea

• Orthostatic hypotension

• Nausea

• Dyskinesia

• Hallucinations

Drug Table

Drug Name	Application	Comments	Image
Entacapone	Parkinson's Disease		"Enter Sign" and "Al Capone"
Tolcapone	Parkinson's Disease	Adverse Effect: Hepatic Necrosis	"Toll Booth" and "Al Capone"