Drug May Cut Parkinson's Disease Disability
Downtime Shorter When Taking Rasagiline With Levodopa, Says Study
March 10, 2005 - An experimental drug called rasagiline may reduce disability in Parkinson's disease patients.
That's the indication of an international 18-week study funded by the drug's maker, Teva Pharmaceutical Industries and H Lundbeck A/S. Rasagiline hasn't been approved by the FDA for the treatment of Parkinson's disease.
The drug is not a cure. Instead, it's intended to help smooth out motor function problems that many Parkinson's patients experience after taking the Parkinson's drug levodopa for a long time.
"Most patients with established Parkinson's disease and sustained treatment with levodopa will eventually have motor fluctuations, defined as periods of the day with poor or absent motor function (off-time) alternating with periods of clearly improved motor function (on-time)," says a study in The Lancet.
What Is Parkinson's Disease?
Parkinson's disease is a progressive, chronic condition. Its cause is unknown.
The disease attacks the cells in the brain that make dopamine, a chemical messenger involved in movements like walking and talking. As a result, dopamine levels drop and the brain's motion signals to the body get scrambled. Symptoms include tremors, slow movement, stiff muscles, aches, and problems with balance and coordination.
Up to a million people in the U.S. have Parkinson's disease, says the Parkinson's Disease Foundation. The disease becomes more common with age, although about 15% of patients are diagnosed before turning 40, says the foundation.
There is no cure for Parkinson's disease. But medications can help manage symptoms. Levodopa, which was developed in the 1960s, has long been considered the most effective medication. It boosts dopamine levels.
Over time, the number of nerve cells producing dopamine in the brain falls. With that, more levodopa is needed to control movement symptoms. Thus the benefit of the drug wears off before the next dose.
Another class of drugs, called dopamine agonists, is also used for Parkinson's symptoms. Which is better -- levodopa or dopamine agonists? That hasn't been settled, but doctors may recommend dopamine agonists as the initial therapy, especially for people younger than 60, because of concerns about levodopa's long-term side effects.
But what if levodopa's long-term problems could be eased? Several drugs are used for this purpose. The new study pitted one of those drugs, Comtan, against rasagiline, which helps stop the breakdown of dopamine.
Participants were 687 Parkinson's patients in Israel, Argentina, and Europe. All were taking levodopa. Participants were randomly assigned to take rasagiline, a placebo, or entacapone along with levodopa for 18 weeks.
Rasagiline and Comtan both reduced "off-time" by about the same amount -- 1.18 hours for rasagiline and 1.2 hours for entacapone. The drugs also boosted "on-time" periods, when motor function was clearly better.
Both drugs also had similar rates of side effects. Half of the patients -- 343 people -- reported "adverse events," says the study, calling 41 cases serious (12 with rasagiline, 12 with Comtan, and 17 with the placebo).