Carbidopa/levodopa/entacapone

Carbidopa/levodopa/entacapone, sold under the brand name Stalevo among others, is a dopaminergic fixed-dose combination medication that contains carbidopa, levodopa, and entacapone for the treatment of Parkinson's disease.

Medical uses
Carbidopa/levodopa/entacapone is indicated for the treatment of Parkinson's disease.

In the European Union it is indicated for the treatment of adults with Parkinson's disease and end-of-dose motor fluctuations not stabilized on levodopa/dopa decarboxylase (DDC) inhibitor treatment.

Side effects
Sometimes a wearing off effect may occur at the end of the dosing interval, where a patient may feel Parkinson's symptoms. Urine, saliva, or sweat may be discolored (dark color such as red, brown, or black) after taking carbidopa/levodopa/entacapone.

Drug interactions
Carbidopa/levodopa/entacapone is contraindicated in patients taking a class of antidepressant drugs known as non-selective monoamine oxidase (MAO) inhibitors such as phenelzine and tranylcypromine.

Carbidopa/levodopa/entacapone may be combined with the drugs rasagiline or selegiline. These drugs are a different type of MAO inhibitor known as selective MAO inhibitors that are often prescribed for Parkinson's disease. Many drug interactions involving selegiline are theoretical, primarily based on interactions with non-selective MAO inhibitors; at oral doses the risk of these interactions may be very low. However, transdermal selegiline, known by its trade name Emsam, is still contraindicated. Transdermal selegiline results in higher plasma levels at which it behaves like a non-selective MAO inhibitor. Concominant use of entacapone, a component of carbidopa/levodopa/entacapone, with MAO inhibitors may increase toxicity of MAO inhibitors. Levodopa, also a component of carbidopa/levodopa/entacapone, in combination with MAO inhibitors may result in hypertensive reactions.

Mechanism of action
Levodopa is the immediate precursor to dopamine. Entacapone is a selective, reversible catechol-O-methyltransferase (COMT) inhibitor that prevents the degradation of levodopa. Entacapone does not cross the blood–brain barrier. Carbidopa is a peripheral aromatic L-amino acid decarboxylase (AADC) inhibitor. Carbidopa, which also does not cross the blood–brain barrier, is combined with levodopa to prevent its conversion to dopamine in the periphery.

Legal status
Carbidopa/levodopa/entacapone was approved by the US Food and Drug Administration (FDA) in June 2003.

Research
It may help decrease a change of response to Parkinson's medications.