For more than 40 years, a drug called levodopa has been the most effective treatment for the uncontrolled movements associated with Parkinson’s disease. Many Parkinson’s patients have taken a pill form of the medicine – also known as L-dopa – for years to control their motor fluctuations.
But the pills can lose effectiveness over time, greatly reducing their value for people in the later stages of the disease.
Now there’s a new form of the drug that is making a positive difference for some Parkinson’s patients. Duopa is a drug that’s delivered continuously by a pump system instead of pills.
“This takes care of the fluctuations in the movement symptoms that advanced Parkinson’s patients experience on a daily basis, and they don’t have to rely on pills while the pump is on,” said movement disorders specialist Dr. Mustafa Saad Siddiqui, an associate professor of neurology at Wake Forest Baptist. “It can mean a very significant improvement in the quality of life of these patients.”
Parkinson’s disease is a degenerative disorder of the brain cells (neurons) that produce dopamine, a chemical that helps people control body movements. While tremors are the best-known sign of Parkinson's, it can also cause muscle rigidity and slowing of movement. There is no cure for the disease, which afflicts approximately 1 million people in the United States, including actor Michael J. Fox and boxing legend Muhammad Ali.
Traditional Treatment of Parkinson’s Disease
The levodopa in pills is absorbed in the blood from the small intestine and travels through the bloodstream to the brain, where it is converted into dopamine and stored in neurons.
In the initial stages of Parkinson’s, the brain still has some neurons capable of producing and storing dopamine. The levodopa pills – which usually contain a drug called carbidopa to reduce nausea and other side effects – give the brain a boost to ensure a sufficient supply of dopamine, thus promoting normal motor control.
But during the disease’s more advanced stages, there aren’t enough neurons left to produce or store enough dopamine. As a result, patients must take more and more levodopa pills in order to supply the brain with adequate levels. At the same time, Parkinson’s causes stomach functions to become slow and unpredictable, which can delay or even prevent the medicine in the pills from leaving the stomach and reaching the bloodstream in the small intestine. Consequently, later-stage Parkinson’s patients are subject to more frequent and more pronounced motor fluctuations.
New Treatment Offers Improved Quality of Life
Duopa has proven capable of addressing those problems.
A gel form of levodopa and carbidopa developed by AbbVie Inc., Duopa is delivered by an external pump directly into the small intestine through a surgically placed tube. The Parkinson’s patient wears a small pouch that holds the pump and a drug cartridge. The Duopa is delivered continuously at a consistent level for up to 16 hours according to a schedule programmed into the pump.
Siddiqui said he monitored the efficacy of the drug and delivery system in Europe, where it has been in use under the name Duodopa since 2004. He directed the clinical trial of Duopa at Wake Forest Baptist as part of the multi-center study which led to its approval by the federal Food and Drug Administration in 2015.
New Treatment Provides Freedom for Patient
Two advocates of Duopa are Parkinson’s patient George Connors and his wife, Kay, of Randleman, North Carolina.
Among the first participants in the clinical trial at Wake Forest Baptist, he has been taking Duopa for more than 5 years now.
“It’s been a lifesaver,” his wife said. “It has made it easier for him to get up and do things.”
Kay said the unreliable action of levodopa pills made it difficult for her husband to pursue activities he loved. But with Duopa, she said, “he goes fishing, mows the yard and does outside work,” all without having to remember when to take the pills.
George gave one example of how Duopa works better for him than pills. He said it used to take him as much as an hour each morning to stand up properly because his toes would cramp overnight and the levodopa pills were slow to work. With the Duopa pump system, he said, his toe cramps are gone within minutes.
Siddiqui said that new drugs and new delivery methods for existing drugs can relieve many of the symptoms experienced by people with Parkinson’s and that ongoing research holds hope for the future.
“Out of all the neurological diseases, we are finding Parkinson’s to have more and more treatments available,” he said.