[3] Carbidopa/levodopa/entacapone (Stalevo), a medication developed by Orion Pharma and marketed by Novartis, is a single tablet formulation that contains levodopa, carbidopa, and entacapone.

[4] Entacapone is used in addition to levodopa and carbidopa for people with Parkinson's disease to treat the signs and symptoms of end-of-dose "wearing-off.

"[5] "Wearing-off" is characterized by the re-appearance of both motor and non-motor symptoms of Parkinson's disease occurring towards the end of a previous levodopa and carbidopa dose.

[2] Episodes of orthostatic hypotension have been shown to be more common at the start of entacapone use due to increased levels of levodopa.

[2] Post-marketing data shows that entacapone may change or worsen mental status, leading to behaviors such as delusions, agitation, confusion, and delirium.

[2] People taking entacapone may experience increased urges to participate in gambling, sexual activities, money spending, and other stimulating reward behaviors.

In theory, it could interact with MAO inhibitors, tricyclic antidepressants and noradrenaline reuptake inhibitors because they also increase catecholamine levels in the body, with drugs being metabolized by COMT (for example methyldopa, dobutamine, apomorphine, adrenaline, and isoprenaline), with iron because it could form chelates, with substances binding to the same albumin site in the blood plasma (for example diazepam and ibuprofen), and with drugs being metabolized by the liver enzyme CYP2C9 (for example warfarin).

None of the medications tested in studies have shown clinically relevant interactions, except perhaps warfarin for which a 13% (CI90: 6–19%) increase in INR was seen when combined with entacapone.

[2] COMT eliminates biologically active catechols present in catecholamines (dopamine, norepinephrine, and epinephrine) and their hydroxylated metabolites.

[2] For the treatment of Parkinson's disease, entacapone is given as an adjunct to levodopa and an aromatic amino acid decarboxylase inhibitor, carbidopa.