Published online by Cambridge University Press: 06 October 2020
• Comtan, Stalevo
• Antiparkinson agent
Commonly Prescribed for
(FDA approved in bold)
• Parkinsonism, including Parkinson’s disease (PD)
How the Drug Works
• Highly selective peripherally acting inhibitor of catechol-O-methyltransferase (COMT), an important enzyme in dopamine metabolism. Use with carbidopa-levodopa enables more levodopa to enter the brain and prevents the end-of-dose wearing-off seen in PD. Entacapone has less activity on COMT in the brain, meaning the drug is not considered centrally active
How Long Until It Works
• PD: hours to weeks
If It Works
• PD: a majority (58%) of patients taking 800 mg or more per day of levodopa will lower levodopa dose, on average by 25% of the total after starting entacapone
If It Doesn't Work
• If end-of-dose wearing-off does not improve with entacapone and levodopa, decrease the dosing interval, add a dopamine agonist or monoamine oxidase B (MAO-B) inhibitor, or consider neurosurgical options. For sudden, unpredictable wearing-off, consider apomorphine
Best Augmenting Combos for Partial Response or Treatment-Resistance
• Entacapone is used only as an adjunctive medication in PD with levodopa
• For dyskinesias, lower dose of levodopa or add a dopamine agonist
• Younger patients with bothersome tremor: anticholinergics may help
• For severe motor fluctuations and/or dyskinesias with good “on” time, functional neurosurgery is an option
• Amantadine may help suppress dyskinesias, although benefit is often short-lived
• Depression is common in PD and may respond to low-dose SSRIs
• Cognitive impairment/dementia is common in mid-late stage PD and may improve with acetylcholinesterase inhibitors
• None required
ADVERSE EFFECTS (AEs)
How the Drug Causes AEs
• COMT inhibition increases the level and duration of action of levodopa
• (Entacapone alone) diarrhea (usually mild to moderate), dyspnea, weakness. May increase levodopa-related AEs such as dyskinesias, nausea, orthostatic hypotension, and hallucinations
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