The drug Sinemet relieves Parkinson’s disease symptoms such as tremor, difficulty swallowing and an awkwardly shuffling gait, but it becomes less effective over time.

Breakthrough: There’s a new way of getting Sinemet’s active ingredient, levodopa, to last longer and more consistently to control Parkinson’s symptoms. It has been available in Canada, Australia and throughout Europe for a few years and, finally, it is now available here in America.

IMPROVING A DRUG’S STAYING POWER

Parkinson’s disease happens when certain brain cells degenerate and produce less dopamine, a chemical necessary to control muscle movement. Levodopa is meant to replace that lost dopamine, but it wears off within minutes. The pill Sinemet contains levodopa plus a drug called carbidopa that helps the levodopa last longer and get to where it needs to go—the brain. It is initially very effective in controlling Parkinson’s symptoms, but within four to six years of starting treatment, it’s effectiveness wears off for roughly 40% of patients. By nine years, 90% of patients are showing troublesome symptoms again. And besides the Parkinson’s symptoms, the body begins to react poorly to the unevenness of levodopa levels…erratic muscle movements (a condition called dyskinesia) begin to occur either when the level of levodopa peaks in the body after taking a dose or when it wears off between doses.

A better—albeit invasive—way to receive levodopa that minimizes these problems was finally approved by the FDA in January 2015 after being available for several years in many other countries around the world. The treatment is a process called carbidopa-levodopa enteral suspension (CLES), marketed as Duopa. It involves surgery to insert a tube through the abdomen into the small intestine. The tube is connected to an external portable pump that a person can carry in his or her pants pocket or some other wearable pouch while the pump delivers a constant flow of the carbidopa-levodopa during waking hours.

THE BENEFITS AND RISKS

Although studies have shown that the CLES system works well to control Parkinson’s symptoms in people with advanced disease, how safe and tolerable is it over the long term? A team of researchers from three top medical institutions—University of Kentucky Medical Center, Cleveland Clinic and Northwestern University Feinberg School of Medicine—along with researchers associated with the drug’s manufacturer, AbbVie Inc., closely examined symptoms and patient quality of life before and after beginning CLES. Side effects of CLES were also examined.

In the first part of the study, which lasted three months, patients on Sinemet were compared with patients receiving CLES. In the second part of the study, the patients who had been on Sinemet were switched to CLES, and all the patients—those who had been on CLES and those new to it–were followed for a year.

The results: Patients put on the CLES system during the first part of the study averaged 12 symptom-free hours a day, compared with an average of 10 hours for patients on Sinemet. Once patients on Sinemet were switched to the CLES system, they also improved to meet the sustained 12-hour window of symptom control. Symptoms were less severe, and dyskinesia—the main debilitating side effect of Sinemet—was much less common once the patients were switched to CLES.

Most side effects were related to surgery rather than CLES use. In fact, serious side effects, such as intestinal perforation during surgery, were common, occurring in 23% of patients. In addition, infection at the surgical site occurred in 18% but cleared up with antibiotic therapy.

Besides surgical side effects, the most common side effects for those new to CLES were abdominal pain, which affected 42% of the patients. Nausea was also common, as was skin redness at the site of the tube insertion, which cleared up in some patients over time.

Since CLES is relatively new, doctors don’t yet know exactly how long, in terms of years, the therapy will provide symptom control for patients with Parkinson’s disease. The lead author of the study, John T. Slevin, MD, from the University of Kentucky Medical Center, told Daily Health News that it is expected that, as the disease progresses and more brain cells that produce dopamine are lost, the benefits of CLES will eventually ebb. CLES simply helps extend symptom control and quality of life longer when other treatments lose their effectiveness.

If you or a loved one has an interest in CLES to control worsening Parkinson’s disease, consult an experienced neurologist who specializes in movement disorders who will work with a gastroenterologist skilled in gastrointestinal surgery. You can find Parkinson’s Disease Centers of Excellence through the National Parkinson Foundation.