Carbidopa, Levodopa

Brand names: Sinemet CR

Why is Carbidopa, Levodopa prescribed?

Sinemet CR is a controlled-release tablet that may be given to help relieve the muscle stiffness, tremor, and weakness caused by Parkinson's disease. It may also be given to relieve Parkinson-like symptoms caused by encephalitis (brain fever), carbon monoxide poisoning, or manganese poisoning.

Sinemet CR contains two drugs, carbidopa and levodopa. The drug that actually produces the anti-Parkinson's effect is levodopa. Carbidopa prevents vitamin B6 from destroying levodopa, thus allowing levodopa to work more efficiently.

Parkinson's drugs such as Sinemet CR relieve the symptoms of the disease, but are not a permanent cure.

Most important fact about Carbidopa, Levodopa

There is also a regular, non-controlled-release form of Carbidopa, Levodopa, which is called Sinemet. Over a period of hours, Sinemet CR, the controlled-release form, gives a smoother release of the drug than regular Sinemet. If you have been taking regular Sinemet, be aware that you may need a somewhat higher dosage of Sinemet CR to get the same degree of relief. Your first morning dose of Sinemet CR may take as much as an hour longer to start working than your first morning dose of regular Sinemet.

How should you take Carbidopa, Levodopa?

Take Sinemet CR after meals, rather than before or between meals. Swallow the tablets whole without chewing or crushing them.

Sinemet CR releases its ingredients slowly over a period of 4 to 6 hours. It is important to follow a careful schedule, taking your doses at the same time every day.

You should not change the prescribed dosage or add another product for Parkinson's disease without first consulting your doctor.

Sinemet CR works best when there is a constant amount in the blood. Try not to miss any doses, and take them at evenly spaced intervals day and night.

  • If you miss a dose...If you forget to take a dose, take it 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. Do not take 2 doses at once.
  • Storage instructions...Store at room temperature in a tightly closed container.

What side effects may occur?

Side effects from Sinemet CR cannot be anticipated. If any develop or change in intensity, inform your doctor immediately.

Only your doctor can determine if it is safe for you to continue taking Sinemet CR.

  • Side effects may include:Confusion, hallucinations, nausea, uncontrollable twitching or jerking

Why should Carbidopa, Levodopa not be prescribed?

Do not take Sinemet CR if you are sensitive to or have ever had an allergic reaction to its ingredients.

Sinemet CR should not be prescribed if you have a suspicious, undiagnosed mole or a history of melanoma.

Special warnings about Carbidopa, Levodopa

Make sure your doctor knows if you have any of the following:

Bronchial asthmaCardiovascular or lung disease (severe)Endocrine (glandular) disorderHistory of heart attack or heartbeat irregularityHistory of active peptic ulcerKidney disorderLiver disorderWide-angle glaucoma (pressure in the eye)

Your doctor will monitor your liver, blood, kidney and heart functions during extended therapy with Sinemet CR.

If you have been taking levodopa alone, you should stop taking levodopa for at least 12 hours before starting to take Sinemet CR.

The carbidopa contained in Sinemet CR cannot eliminate side effects caused by levodopa. Since carbidopa helps levodopa reach your brain, Sinemet CR may, in fact, produce some levodopa side effects—particularly twitching, jerking, or writhing—sooner and at a lower dosage than levodopa alone or even regular Sinemet. If such involuntary movements develop while you are taking Sinemet CR, you may need a dosage reduction.

Like levodopa, Sinemet CR may cause depression. Make sure your doctor knows if you have mental or emotional problems.

Muscle rigidity, high temperature, rapid heartbeat or breathing, sweating, blood pressure changes, and mental changes may occur when Sinemet CR is reduced suddenly or discontinued. If you stop taking Carbidopa, Levodopa abruptly, your doctor should monitor your condition carefully.

You may see a red, brown, or black coloration in your saliva, urine, or sweat. This is not harmful, but may stain your clothes. Too much stomach acid can interfere with absorption of the medication.

Possible food and drug interactions when taking Carbidopa, Levodopa

If Sinemet CR 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 Sinemet CR with the following:

AntacidsAntiseizure drugsAntispasmodic drugsBlood pressure medicationsHigh-protein foodsIsoniazidMajor tranquilizers such as haloperidol or risperidoneMAO inhibitors such as the antidepressants phenelzine and tranylcypromine and the Parkinson's drug selegilineMethionine drugsMetoclopramidePapaverinePyridoxine (vitamin B6)Tranquilizers such as alprazolamTricyclic antidepressants

If you have been taking an MAO inhibitor such as phenelzine or tranylcypromine, you must discontinue it at least 2 weeks before starting to take Sinemet CR.

A high-protein diet may impair the effectiveness of Sinement CR. Iron supplements can also reduce its effect.

Special information if you are pregnant or breastfeeding

If you are pregnant or plan to become pregnant, inform your doctor immediately. Sinemet CR should be used during pregnancy only if the benefit outweighs the potential risk to the unborn child. It is not known whether Sinemet CR appears in breast milk. If Carbidopa, Levodopa is essential to your health, your doctor may advise you to stop nursing your baby until your treatment with Carbidopa, Levodopa is finished.

Recommended dosage for Carbidopa, Levodopa

Your doctor will tailor your individual dosage carefully, depending on your response to previous therapy and symptoms.


For patients with mild to moderate symptoms, the initial recommended dose is 1 tablet of Sinemet CR taken 2 times a day.

Starting doses should be spaced out every 4 to 8 hours and then adjusted to each patient's individual response.

The usual long-term dose is 2 to 8 tablets per day, taken in divided doses every 4 to 8 hours during the waking day.

Higher doses (12 or more tablets per day) and shorter intervals (less than 4 hours) have been used, but are not usually recommended.

When doses of Sinemet CR are given at intervals of less than 4 hours, and/or if the divided doses are not equal, it is recommended that the smaller doses be given at the end of the day.

An interval of at least 3 days between dosage adjustments is recommended.

Dosage adjustment of Sinemet CR may be necessary if your doctor prescribes additional medications.


Use of Sinemet CR in children under 18 is not recommended.


Too much Sinemet CR may cause muscle twitches, inability to open the eyes, or other symptoms of levodopa overdosage. Like other medications, Sinemet CR taken in excess can have serious consequences. If you suspect symptoms of a Sinemet CR overdose, seek medical attention immediately.