Duopa (carbidopa and levodopa) for Parkinson’s disease
Fact-checked by What is Duopa for Parkinson’s disease?
Duopa (carbidopa and levodopa enteral suspension) is an approved combination therapy used to treat motor symptom fluctuations in people with advanced Parkinson’s disease. It comes as an intestinal gel that is administered directly into the small intestine via a surgically implanted tube.
In Parkinson’s, nerve cells that produce the chemical messenger dopamine gradually die off, leading to various motor and non-motor symptoms. A mainstay of treatment is levodopa, a molecule that the brain can convert into dopamine to replenish low levels. Levodopa is often combined with carbidopa, which helps boost levodopa’s efficacy by enabling more of it to reach the brain.
Some people taking oral levodopa and carbidopa, particularly those in more advanced disease stages, start to experience periods where motor symptoms start to return as the medications wear off between doses. There are known as off episodes.
Duopa aims to minimize these motor fluctuations by providing the body with a continuous supply of the medications for 16 waking hours each day. Because it goes directly into the small intestine, where most levodopa is absorbed, it may provide more steady symptom control than oral formulations that must first be processed in the stomach.
Abbvie markets Duopa, which is also available in other regions under the brand name Duodopa.
Therapy snapshot
| Brand name | Duopa |
| Chemical name | Carbidopa and levodopa enteral suspension |
| Usage | Used to treat motor fluctuations in advanced Parkinson’s disease |
| Administration | Continuous delivery as an intestinal gel |
Who can take Duopa?
In the U.S., Duopa is approved for treating motor fluctuations in people with advanced Parkinson’s disease. The therapy holds similar approvals in Europe and Canada.
The prescribing information for Duopa notes that the medication is contraindicated, or not recommended, for people who are currently taking nonselective monoamine oxidase (MAO) inhibitors — a class of antidepressant medications — or have taken them in the past two weeks.
Duopa is also usually not recommended for people with a history of a major psychotic disorder because the medication can exacerbate symptoms.
How is Duopa administered?
Duopa is available as an intestinal gel suspension that comes in single-use cassettes. It is delivered as a continuous infusion through a surgically implanted tube controlled by an external pump.
The surgery is called a percutaneous endoscopic gastrostomy with jejunal tube, or PEG-J. A specialist makes a small opening in the stomach wall, through which a tube is passed into the small intestine. The tube is attached to an external pump that controls the medication delivery.
The Duopa dosage is then individualized under medical supervision, with a maximum of 2,000 mg levodopa (one cassette) daily. This daily dose may include:
- morning dose: a larger initial dose is delivered over 10 to 30 minutes
- continuous dose: the rest of the medication is slowly delivered over 16 waking hours
- extra doses: small booster doses can be given as needed to control symptom fluctuations
At the end of the infusion, patients will disconnect the pump from the delivery port, flush it with drinking water, and take their prescribed nighttime dose of oral carbidopa-levodopa. Patients will receive more detailed Duopa infusion instructions, including training on how to attach and store Duopa cassettes, before starting treatment.
Prior to initiating Duopa, individuals who are using extended-release oral formulations of carbidopa and levodopa must transition to an immediate-release formulation.
While long-term Duopa treatment requires a PEG-J tube, the medication can be given for a short time before surgery through a tube that goes from the nose to the small intestine (nasojejunal tube). This can help doctors evaluate a person’s response to the medication before deciding to proceed with Duopa surgery and treatment.
Duopa in clinical trials
Duopa’s approval was based on data from two identically designed Phase 3 clinical trials — NCT00357994 and NCT00660387 — that were later merged into a single trial involving 71 people with advanced Parkinson’s who were experiencing persistent motor fluctuations on an optimized regimen of carbidopa-levodopa.
Participants received either Duopa and a placebo oral pill, or a placebo intestinal suspension and oral immediate-release carbidopa-levodopa pills for three months. The results showed that compared with oral treatment, Duopa:
- led to significant reductions in daily off time by a mean of nearly two hours
- significantly increased on time without troublesome dyskinesia — periods of good symptom control without the unwanted movements that can be a side effect of levodopa — by nearly two hours
In a subsequent open-label extension study (NCT00360568), reductions in off time observed in the main trial were sustained over another year of Duopa treatment, while on time without troublesome dyskinesia continued to increase. For those who switched from oral treatment to Duopa, improvements in both measures were observed.
Duopa side effects
The most common Duopa and Duopa pump side effects include:
- complications with device insertion
- nausea
- depression
- swelling (edema) in the hands and feet
- high blood pressure
- upper respiratory tract infections
- throat pain
- collapse of the tiny air sacs in the lungs (atelectasis)
- redness at the incision site
The medication also comes with warnings and precautions for other potentially serious side effects, for which patients will be carefully monitored. These include:
- gastrointestinal complications from the implantation surgery, which could require surgery or be life-threatening
- excessive drowsiness or falling asleep during everyday activities
- low blood pressure when standing up (orthostatic hypotension) and fainting
- new or worsening hallucinations and psychotic-like behavior
- problems with impulse control or strong compulsions
- depression and/or suicidal thoughts or behaviors
- new or worsening dyskinesia
- vitamin B6 deficiency, which can cause seizures
- nerve damage
- cardiovascular complications
- increased pressure in the eye for people with glaucoma, an eye disease
- abnormal lab tests, including markers of kidney or other organ damage
Patients should inform their healthcare provider immediately if they experience abdominal pain, prolonged constipation, nausea, vomiting, fever, or black, tarry stool, as these could be signs of a complication related to the implanted delivery tube.
If certain side effects occur, a doctor may recommend adjusting the dosage or discontinuing Duopa treatment. Duopa should only be discontinued under medical supervision — rapid discontinuation can cause serious withdrawal symptoms, including high fever and confusion.
Duopa may interact with other medications, including MAO-B inhibitors, which may require dose adjustments or careful monitoring. Patients should tell their care providers about all medications they are using.
Parkinson's News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
