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Generic names: carbidopa and levodopa [KAR-bi-DOE-pa-and-LEE-voe-DOE-pa]
Brand names: Sinemet, Sinemet CR
Drug class: dopaminergic antiparkinsonism agents

What is Sinemet?

Sinemet is a combination of levodopa and carbidopa. Sinemet treats symptoms of Parkinson’s disease, such as muscle stiffness and spasms. Parkinson's may be caused by low levels of dopamine in the brain.

Sinemet can also be used to treat Parkinson's symptoms that are caused by carbon dioxide, carbon monoxide poisoning, or manganese intoxication.


Sinemet should not be used if you suffer from narrow-angle glaucoma. Sinemet should not be used if you've taken an MAO inhibitor in the last 14 days. Examples include isocarboxazid injection, linezolid injection, phenelzine, or tranylcypromine.

Before you take this drug

Sinemet should not be used if:

  • Narrow-angle glaucoma.

Sinemet should not be used if MAO inhibitors have been taken in the last 14 days. It is possible that a dangerous drug interaction will occur. MAO inhibitors are isocarboxazid and linezolid.

Tell your doctor about any of the following to ensure that Sinemet will be safe for you:

  • High blood pressure or a heart attack.
  • Liver or kidney disease
  • An endocrine (hormonal) disorder;
  • Asthma (a chronic respiratory disease) or another breathing disorder.
  • A stomach or intestinal ulcer
  • Open-angle glaucoma
  • Depression, mental illness, or psychosis.

Parkinson's patients may be at a greater risk for skin cancer (melanoma). Speak to your doctor to learn more about the risk of skin cancer and to be aware of any symptoms.

Inform your doctor if you are pregnant or nursing. The disintegrating tablets may contain phenylalanine. Inform your doctor if phenylketonuria is present.

How to take Sinemet?

Follow all instructions listed on your prescription label, read all medication guides or instruction sheets provided with it and carefully consider all instructions that come with your medication. Sometimes your doctor will change the dose. You must wait at least 12 hours before starting Sinemet if you are already taking levodopa. Sinemet may be taken either with or without food. To maintain a constant amount of drugs in your system, take your doses regularly.

Breaking the tablet in half to achieve a precise dosage may be necessary. Never chew or crush a tablet. Sinemet may take several weeks to improve your symptoms. To get the best results, use the medication according to the instructions. If your symptoms don't improve after a couple of weeks, talk to your doctor. Tell your doctor if you notice that the effects of the medication wear off rapidly between doses.

You may need to visit your doctor more often if you take Sinemet for a long time. It can also affect certain medical tests. Inform any doctor that treats you about your Sinemet use. Sinemet withdrawal symptoms can be unpleasant if you suddenly stop taking it. You should ask your doctor about how to safely discontinue this medication. Store away from moisture, heat, and light at room temperature.

Details on dosage

Adult dosage for Parkinson's disease:

The optimal dosage is determined through careful individual titration. All doses are expressed as CARBIDOPA/LEVODOPA.
Immediate-release tablets:
Initial dose: orally, 25–100 mg three times daily or 10–100 mg four times a week.
Increase the dose by 1 tablet daily or every other day as necessary until 8 tablets are reached. You can use tablets in both ratios (1 to 4 or 1 to 10) for an optimal dose.
Conversion to LEVODOPA
Carbidopa and levodopa can be started with 25% of the previous dose.
Patients receiving less than 1500 mg of levodopa per day should take 25–100 mg orally, 3–4 times daily.
Patients receiving more than 1500 mg of levodopa per day should take 25 mg to 250 mg three or four times daily.
Sinemet CR Tablets:
Initial dose (levodopa naive): 50–200 mg twice daily; the initial dosage should not be taken at intervals greater than 6 hours.
The dose and the interval between dosing may be increased or reduced at intervals of at least three days, depending on the therapeutic response.
Dosage range: The majority of patients require 400–1600 mg/day, divided into 4–8-hour intervals during the waking hours. Although doses as high as 2400 mg/day have been administered at intervals less than four hours apart, they are not generally recommended.
Conversion to immediate release levodopa, with or without a decarboxylase inhibitor:
For patients taking levodopa and a decarboxylase inhibitor, the dosage of Sinemet should be about 10% higher than that prescribed previously. This may be increased by up to 30%, depending on the clinical response.
Levodopa must be stopped at least 12 hours prior to starting carbidopa or levodopa for patients who do not have a decarboxylase inhibitor.

What happens if I miss the dose?

If it is nearly time for your next dose, forgoing one is best. Never take two doses of the same medicine at once. Refill your prescription before you run out.

What happens if I overdose?

Call 1-800-222-1222 for poison help or seek immediate medical attention.

What should be avoided?

Do not drive or engage in hazardous activities until you have a better understanding of how Sinemet affects you. You may have impaired reactions. You may feel dizzy if you get up quickly from a seated or lying position.

Avoid iron supplements and eat a high-protein diet (proteins include meat, cheese, eggs, etc.). This can make it more difficult for your body to absorb and digest carbidopa or levodopa. Speak to your doctor or a dietitian for advice on the best foods you can eat when taking this medication.

Side effects of Sinemet

If you experience any of the following symptoms of an allergy to Sinemet, seek immediate medical attention: hives, difficulty breathing, swelling of your lips, face, tongue, or throat.

If you experience:

  • Uncontrolled facial movements (such as lip smacking and frowning; tongue movements, blinking, or eye movements);
  • Tremors that are worsening (uncontrolled shaking)
  • Severe or persistent diarrhoea or nausea.
  • Confusion, hallucinations, or unusual changes in mood and behaviour
  • Depression or suicidal feelings;
  • Severe nerve system reaction: stiff muscles (rigid), high fever, sweating and confusion, rapid or irregular heartbeats Tremors. Feeling like you may pass out.

Sinemet can cause some people to fall asleep while doing normal activities during the day, such as driving, working, talking, or eating. Speak to your doctor if daytime sleepiness is a problem. While taking this medication, you may experience increased sexual desire, urges to gamble, or other intense desires. If this happens, talk to your doctor.

Your urine, saliva, or sweat may appear dark, like red, brown, or black. It is not harmful, but your clothing or bed sheets may be stained.

Sinemet may cause side effects such as:

  • The jerky or twisting of muscle movements
  • Headache, dizziness;
  • Low blood pressure (feeling a little light-headed)
  • Sleep problems, strange dreams;
  • Dry mouth
  • Muscle contractions
  • Nausea, vomiting, and constipation.

There may be other side effects. For medical advice on side effects, call your doctor. The FDA can be contacted at 1-800-FDA-1088 to report side effects.

Interaction with other drug

Carbidopa or levodopa may interact with other drugs, such as prescription and over-the-counter medicines, vitamins, and herbal products. Inform your doctor of all the medicines you are taking, as well as any new ones.



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