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Drugs reference index «Comtan»


Generic name: EntacaponeBrand names: Comtan

Why is Comtan prescribed?

Comtan is used for Parkinson's disease. It is prescribed when doses of the combination drug levodopa/carbidopa (Sinemet) begin to wear off too soon. By extending the effect of each dose of Sinemet, it frees the patient from the stiffness and tremors of Parkinson's for a longer period of time.

Comtan works by inhibiting the effect of an enzyme that breaks down the levodopa in Sinemet. It has no effect on Parkinson's disease when used by itself.

Most important fact about Comtan

Comtan's value lies in its ability to extend Sinemet's effectiveness when it begins to decline. It is helpful only when taken with the other drug, and has no benefit when used alone.

How should you take Comtan?

Comtan should be taken with each dose of Sinemet. It can be taken up to 8 times per day, with or without food.

  • If you miss a dose...Take it along with a dose of Sinemet as soon as you remember. If it is almost time for your next dose, skip the one you missed and go back to your regular schedule. Never take 2 doses at the same time.
  • Storage instructions...Store at room temperature.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Comtan.

  • Side effects may include:Abdominal pain, back pain, constipation, diarrhea, discoloration of urine, dizziness, nausea, onset of new movement disorders, tired feeling, vomiting

Why should Comtan not be prescribed?

If Comtan gives you an allergic reaction, you won't be able to use it. It is prescribed only with caution for people with liver disease.

Special warnings about Comtan

Use of Comtan can cause low blood pressure, with symptoms such as dizziness, nausea, fainting, and sweating. Be careful when standing up after you have been sitting or lying down. See how the medication affects you before you drive a car or operate machinery.

Nausea and diarrhea are especially common side effects of Comtan, developing in more than 10 percent of those taking it. In rare cases, the problem is severe. Comtan may also cause hallucinations, and occasionally triggers new movement disorders. In about 10 percent of those taking it, it has the harmless side effect of turning the urine a brownish-orange color.

An abrupt discontinuation of Comtan can cause a reappearance of Parkinson's symptoms. If a decision is made to discontinue the drug, it should be withdrawn slowly, under a doctor's supervision.

This drug is not intended for use in children.

Possible food and drug interactions when taking Comtan

If Comtan is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Comtan with the following:

Antidepressant drugs classified as MAO inhibitors, including phenelzine and tranylcypromine (Comtan can be used with a special type of MAO inhibitor called selegiline, which is used for treating Parkinson's disease)BitolterolCertain antibiotics, including ampicillin and erythromycinCholestyramineMethyldopaIsoproterenolProbenecid

Special information if you are pregnant or breastfeeding

The possibility of damage to a developing baby has not been ruled out. Tell your physician immediately if you are pregnant or plan to become pregnant. Comtan may appear in breast milk. It should be used with caution if you are nursing your baby.

Recommended dosage for Comtan


The recommended dose is one 200-milligram tablet with each dose of Sinemet, up to a maximum of 8 doses per day. If you were taking more than 800 milligrams of levodopa per day before starting Comtan, you will probably need a reduction in your levodopa dose once you begin taking the drug.


Little is known about the result of Comtan overdose. However, the results could be serious, so if you suspect an overdose, seek medical attention immediately.

  • Comtan Prescribing Information (FDA)
  • Comtan MedFacts Consumer Leaflet (Wolters Kluwer)
  • Comtan Concise Consumer Information (Cerner Multum)
  • Comtan Advanced Consumer (Micromedex) - Includes Dosage Information
  • Entacapone Professional Patient Advice (Wolters Kluwer)

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