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Generic name: carbidopa and levodopa ( [ kar-bi-DOE-pa, lee-voe-DOE-pa ]
Drug class: Dopaminergic antiparkinsonism agents

Medically reviewed by Last updated on Apr 26, 2022.

Commonly used brand name(s)

In the U.S.

  • Duopa

Available Dosage Forms:

  • Suspension

Therapeutic Class: Antiparkinsonian

Pharmacologic Class: Decarboxylase Inhibitor

Uses for Duopa

Carbidopa and levodopa enteral suspension is used to treat motor fluctuations in patients with advanced Parkinson's disease. Parkinson's disease is a disorder of the central nervous system (brain and spinal cord).

Dopamine is a naturally occurring substance in the brain that helps provide control of movement and activities such as walking and talking. In patients with Parkinson's disease, there is not enough dopamine in some parts of the brain. Levodopa enters the brain and helps replace the missing dopamine, which allows people to function better. By increasing the amount of dopamine in the brain, levodopa helps control symptoms and helps you to perform daily activities such as dressing, walking, and handling utensils.

This medicine is available only with your doctor's prescription.

Before using Duopa

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of levodopa and carbidopa combination in the pediatric population. Safety and efficacy have not been established.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of Duopa® in the elderly. However, elderly patients are more likely to have kidney problems, which may require caution in patients receiving this medicine.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Bromopride
  • Clorgyline
  • Furazolidone
  • Iproniazid
  • Isocarboxazid
  • Linezolid
  • Methylene Blue
  • Moclobemide
  • Nialamide
  • Pargyline
  • Phenelzine
  • Procarbazine
  • Sulpiride
  • Toloxatone
  • Tranylcypromine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Amisulpride
  • Bupropion
  • Haloperidol
  • Isoniazid
  • Macimorelin
  • Metoclopramide
  • Olanzapine
  • Sapropterin

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Droxidopa
  • Fosphenytoin
  • Indinavir
  • Iron
  • Kava
  • Phenylalanine
  • Phenytoin
  • Spiramycin
  • Tyrosine

Interactions with food/tobacco/alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

  • High Protein Food

Other medical problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Arrhythmia (heart rhythm problem) or
  • Depression, history of or
  • Dyskinesia (abnormal muscle movements) or
  • Glaucoma or
  • Heart attack, history of or
  • Heart disease or
  • Hypertension (high blood pressure) or
  • Neuropathy (nerve problems) or
  • Psychosis (mental disorder), or history of or
  • Sleep disorders or
  • Stomach or bowel problems (eg, bezoar, ileus, bowel blockage, perforation, post operative wound infection, ulcers)—Use with caution. May make these conditions worse.
  • Melanoma (skin cancer), suspicious or a history of or
  • Skin lesions, undiagnosed (rashes that involve changes in color or texture of the skin)—Should not be used in patients with these conditions.

Proper use of Duopa

Use this medicine exactly as directed by your doctor. Do not use it more often or longer than your doctor ordered.

This medicine should come with a Medication Guide and patient instructions. Read and follow these instructions carefully. Ask your doctor if you have any questions.

Duopa® comes in a small, plastic container called cassette. This medicine is given continuously for 16 hours through a tube that is put into your stomach called a PEG-J. A small portable pump (CADD-Legacy 1400) is used to move Duopa® from the cassette through your PEG-J tube. It may also be given for a short time using a tube through your nose called a naso-jejunal (NJ) tube. Your doctor will show you how to use Duopa® and the portable pump before you use it for the first time.

Before using this medicine, your doctor will need to have a procedure to make a small hole in your stomach to place the PEG-J tube. Your doctor will need to ask you if you have had stomach surgery or problems with your stomach before starting this medicine.

Your prescribed dose of Duopa® will be programmed into your pump by your doctor. Your Duopa® dose should only be changed by your doctor.

Keep a supply of carbidopa-levodopa immediate release tablets in case you are not able to get your Duopa® infusion. You will also need these tablets for your prescribed night-time dose after receiving your Duopa® dose.

Since protein may interfere with the body's response to carbidopa and levodopa, high protein diets should be avoided. Intake of normal amounts of protein should be spaced equally throughout the day, or taken as directed by your doctor.

If you are taking multivitamin tablets or plan to start taking them, discuss this first with your doctor. Iron salts (in vitamins) may keep this medicine from working properly.


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For enteral dosage form (suspension):
    • Parkinson's disease:
      • Adults—Dose must be determined by your doctor. The dose is usually not more than 2000 milligrams of levodopa (one cassette) given over 16 hours.
      • Children—Use and dose must be determined by your doctor.

Missed dose

This medicine needs to be given on a fixed schedule. If you miss a dose or forget to use your medicine, call your doctor or pharmacist for instructions.


Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store Duopa® cassette in the refrigerator. Protect it from light. Keep it in the carton before using. When you remove Duopa® cassette from the refrigerator, it should be used within 16 hours. Do not freeze.

Precautions while using Duopa

It is very important that your doctor check your progress at regular visits to allow changes in your dose and to check for any unwanted effects.

Do not take this medicine if you have taken a monoamine oxidase (MAO) inhibitor (eg, phenelzine, tranylcypromine, Nardil®, Parnate®) in the past 2 weeks.

Using this medicine may cause stomach or bowel problems. Call your doctor right away if you have abdominal or stomach pain, constipation that does not go away, nausea, vomiting, fever, or dark, tarry stools.

This medicine may cause dizziness, drowsy, faint, lightheaded, trouble in controlling movements, or trouble in concentrating or seeing clearly. Make sure you know how you react to this medicine before you drive, use machines, or do other jobs that require you to be alert, well-coordinated, or able to think or see well.

Some people who have used this medicine had unusual changes in their behavior. Talk with your doctor right away if you start having problems with gambling or an increased interest in sex while using this medicine.

If you develop any unusual or strange thoughts and behavior while receiving this medicine, be sure to discuss it with your doctor. Other changes might be confusion, worsening of depression, visual hallucinations (seeing things that are not there), suicidal thoughts, and unusual excitement, nervousness, or irritability.

Do not stop taking this medicine without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping completely. This may help prevent a possible worsening of your condition and reduce the possibility of withdrawal symptoms, such as convulsions (seizures), difficulty with breathing, a fast heartbeat, a high fever, high or low blood pressure, increased sweating, loss of bladder control, severe muscle stiffness, unusually pale skin, or tiredness.

Check with your doctor right away if you have burning, numbness, tingling, or painful sensations, weakness in the arms, hands, legs, or feet, or unsteadiness or awkwardness while you are using this medicine. These may be symptoms of peripheral neuropathy.

Check with your doctor right away if you have chest pain or discomfort, irregular heartbeat, nausea or vomiting, pain in the shoulders, arms, jaw, or neck, or sweating after receiving this medicine.

It is important that your doctor check your skin regularly for signs of a skin cancer called melanoma. If you notice any unusual red, brown, or black spots on your skin, talk to your doctor right away.

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Duopa side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  • Blurred vision
  • chills
  • cold sweats
  • confusion
  • discouragement
  • dizziness
  • dizziness, faintness, or lightheadedness when getting up from lying or sitting position
  • feeling sad or empty
  • full feeling
  • headache
  • irritability
  • lack of appetite
  • loss of interest or pleasure
  • nervousness
  • pounding in the ears
  • pressure in the stomach
  • rapid weight gain
  • slow or fast heartbeat
  • swelling of the abdominal or stomach area
  • tingling of the hands or feet
  • tiredness
  • trouble concentrating
  • trouble sleeping
  • twitching, twisting, or uncontrolled repetitive movements of the tongue, lips, face, arms, or legs
  • unusual weight gain or loss

Less common

  • Burning, numbness, tingling, or painful sensations
  • confusion about identity, place, and time
  • dry mouth
  • false beliefs that cannot be changed by facts
  • feeling that others are watching you or controlling your behavior
  • holding false beliefs that cannot be changed by fact
  • hyperventilation
  • irregular heartbeats
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • severe constipation
  • severe mood or mental changes
  • severe vomiting
  • shaking
  • shortness of breath
  • trouble sleeping
  • unsteadiness or awkwardness
  • unusual behavior
  • unusual excitement, nervousness, or restlessness
  • weakness in the arms, hands, legs, or feet


  • Change in size, shape, or color of existing mole
  • mole that leaks fluid or bleeds
  • new mole

Incidence not known

  • Blindness
  • chest pain or discomfort
  • constipation that does not go away
  • convulsions
  • dark, tarry stools
  • decreased vision
  • difficulty with breathing
  • eye pain
  • high fever
  • increased sweating
  • loss of bladder control
  • nausea or vomiting
  • pain in the shoulders, arms, jaw, or neck
  • severe muscle stiffness
  • tearing
  • unusually pale skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Body aches or pain
  • cough
  • difficulty with swallowing
  • ear congestion
  • excess air or gas in the stomach or intestines
  • heartburn
  • loss of voice
  • nasal congestion
  • passing gas
  • redness at the incision site
  • runny nose
  • sneezing
  • sore throat

Less common

  • Acid or sour stomach
  • belching
  • diarrhea
  • heartburn
  • indigestion
  • rash
  • stomach discomfort or upset

Incidence not known

  • Sleepiness
  • unusual drowsiness

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.