Talk with your healthcare provider prior to taking entacapone if you have:
- A bile duct obstruction or gallbladder disease
- Lung problems, such as asthma or chronic obstructive pulmonary disease (COPD)
- Kidney disease, such as kidney failure (renal failure)
- Liver disease, such as liver failure, cirrhosis, or hepatitis
- Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant (see Comtan and Pregnancy)
- Breastfeeding (see Comtan and Breastfeeding).
Make sure to tell your healthcare provider about any other medications you are taking, including prescription and nonprescription medicines, vitamins, and herbal supplements.
(Click Precautions and Warnings With Entacapone to learn more, including information on who should not take the drug.)
Entacapone is always used in combination with carbidopa and levodopa; it has no activity against Parkinson's disease when used alone. The drug works by increasing blood levels of levodopa and helping it to last longer in the body. Entacapone works by inhibiting an enzyme known as catechol-O-methyltransferase (COMT) that breaks down levodopa before it has a chance to reach the brain.
In clinical studies, entacapone plus carbidopa-levodopa has been shown to be more effective than just carbidopa-levodopa for Parkinson's treatment. In these studies, people who were experiencing wearing-off fluctuations of their carbidopa-levodopa therapy were given either entacapone or a placebo (a "sugar pill" with no active ingredient) to take with each dose of their carbidopa-levodopa.
These studies showed that entacapone helped carbidopa-levodopa work longer, with shorter "off" periods (when the medication did not work well) and longer "on" periods (when the medication worked well).