Duopa (Levodopa/Carbidopa) for Parkinson's disease

Overview
Duopa is a prescription drug approved by the Food and Drug Administration (FDA) in 2015 to treat fluctuating motor symptoms in those with advanced Parkinson’s Disease. Duopa may be prescribed if your condition is responsive to dopaminergic treatment, but you have three or more hours of “off” time on your current drug regimen.

Duopa is not appropriate for people with undiagnosed skin lesions, narrow-angle glaucoma, or a history of melanoma, stomach ulcers, or stomach surgery. Duopa is not suitable for use in people who have previously shown hypersensitivity to Levodopa or Carbidopa. Duopa must be used with caution in people with wide-angle glaucoma, diabetes, asthma, emphysema, mental illness, or problems with the heart, kidneys, liver, lungs, or blood vessels. Duopa may not be appropriate for women who are pregnant or breastfeeding.

Duopa is a combination drug containing both Levodopa and Carbidopa. Levodopa is the precursor molecule to the neurotransmitter Dopamine. Levodopa is believed to treat Parkinsonian motor symptoms by increasing the concentration of Dopamine in the brain. Carbidopa is a molecule that inhibits the breakdown of Levodopa into Dopamine before it reaches the brain. Carbidopa is believed to work by increasing the amount of Levodopa that reaches the brain, making Levodopa effective at significantly lower doses.

Some medications are available both as generic and branded products. Although generic and branded formulations of a drug contain the same active ingredients at the same concentrations, your body may react differently to different formulations. Check with your doctor before switching between drug brands or between generic and branded drugs.

How do I take it?
Duopa is infused directly into your small intestine as a gel. At first, you will receive Duopa via a naso-jejunal tube, which is inserted through your nose and down your throat, into your small intestine. If you and your doctor decide that Duopa is beneficial, you will need to undergo minor surgery called percutaneous endoscopic gastrostomy (PEG) to create a small hole with a tube through your upper abdomen. The hole, which is known as a stoma or port, leads to a section of your small intestine called the jejunum. Altogether, the surgery and the portal it creates are called the PEG-J or J-tube. A small pump will be fitted into the stoma, and Duopa will be infused continuously through the pump. A nurse or doctor will teach you how to care for your stoma.

You will administer Duopa by inserting small cassettes containing the drug into the pump. Store Duopa cassettes in the refrigerator. Before inserting a cassette into the pump, allow it to warm to room temperature over 20 minutes. Do not leave a cassette in the pump for longer than 16 hours. Never reuse a cassette, even if it still contains medication. If you need to disconnect the pump for a short period, ask your doctor in advance whether you should administer an extra dose before disconnecting.

Do not begin taking Duopa within two weeks of taking a monoamine oxidase (MAO) inhibitor. If you are switching from Levodopa to Duopa, wait 12 hours after your final dose of Levodopa before you receive your first dose of Duopa.

While you are on Duopa your doctor will order regular blood tests to monitor your liver, kidney, and heart function. Examine your skin regularly for changes and visit your dermatologist regularly to check for signs of melanoma. If you have wide-angle glaucoma, make sure your ophthalmologist regularly monitors your intraocular pressure.

If you experience nausea while on Duopa, ginger tea may help calm your stomach. Avoid taking iron supplements or eating a diet high in protein or fat while taking Duopa. Consuming large amounts of these nutrients can interfere with the body’s absorption of Duopa.

Avoid driving or operating machinery until you are certain you understand how Duopa affects you.

You may experience withdrawal symptoms if you stop taking Duopa suddenly. If you decide to stop taking Duopa, ask your doctor for a plan to decrease your dosage gradually.

Always follow your doctor’s instructions exactly when taking Duopa.

Results
Levodopa/Carbidopa (Duopa) is considered to be the most effective treatment for the motor symptoms of Parkinson’s Disease and some types of Parkinsonism.

Side effects
Due to its method of delivery, Duopa can cause gastrointestinal complications, some of which can become serious or even fatal. Gastrointestinal complications may include wound infection, intestinal perforation, paralysis (ileus), bleeding, or circulation problems (ischemia), pancreatitis, peritonitis, and ulcer or erosion around the tube.

Common side effects of Duopa include nausea, vomiting, diarrhea, constipation, dizziness, drowsiness, nervousness, headaches, confusion, memory problems, nightmares, problems sleeping, sweating, loss of appetite, or changes in the sense of taste. Tell your doctor if these side effects become worse. Duopa may cause your urine, sweat, or saliva to turn dark colors, which can stain clothes.

Inform your doctor immediately if you experience pain in your abdomen or the skin around your stoma, a fast, pounding heartbeat, hallucinations, suicidal thoughts, depression, increased urges to have sex or gamble, stools containing blood or a tarry substance, vomit containing blood or a substance resembling coffee grounds, hoarseness, or abnormal body movements while taking Duopa.

Many drugs can cause allergic reactions that in the most serious cases, can result in death. Seek immediate medical help if you experience signs of a severe allergic reaction such as hives, difficulty breathing, or swelling in the face, throat, eyes, lips, or tongue.