Low doses of pergolide, a drug commonly used to treat Parkinson’s disease, seem to offer relief for sufferers of the sleep disorder Restless Leg Syndrome (RLS). A new study, published in the April issue of the journal Neurology, corroborates previous smaller studies with similar findings. RLS is a sleep disorder and occurs primarily during the night. People with RLS feel an uncomfortable tingling, pain, prickling, crawling, or need to move the lower legs. It is worse after not moving for a long time. RLS is associated with Periodic Limb Movements during Sleep (PLMS), in which a similar motor disorder causes muscle twitches, severe enough to wake the sufferer repeatedly during the night. Both can be relieved by moving the legs. When left untreated, RLS and PLMS can lead to sleep deprivation, daytime fatigue, and insomnia.
Dr. Claudia Trenkwalder and her colleagues performed a randomized, double-blind study of the effects of pergolide on RLS. The study took place at seventeen medical centers located in seven countries in Europe and Australia. Although similar studies have taken place in the last eight years, this is the largest and most extensive of its kind. The two-phase study lasted almost two years.
Because nausea is a common side effect of pergolide, all subjects in the study were first given domperidone, an anti-nausea drug. This helped to insure that patients and doctors did not make assumptions about which treatment was being used. However, nausea and headache were still more common in patients given pergolide than in those given a placebo.
In Phase I, 100 participants were given either a low dose (.25 to .75 mg) of pergolide or a placebo for six weeks. Those who received pergolide showed improvement in both the severity of RLS and PLMS symptoms, and their sleep was more restful than before. Those who responded continued with the same treatment (without knowing what that treatment was) during Phase II.
Patients who did not respond to the treatment in Phase I were prescribed 1.5 mg of pergolide nightly, whether they originally took pergolide or the placebo. During this phase, the participants were aware of the amount and kind of medicine they were taking. Their symptoms showed marked improvement during the year.
Previous studies, published in the late 1990s, showed similar results, but were much shorter and with fewer patients. They lasted from two to six weeks, and involved between eleven and 28 participants.
Pergolide, which is classified as a dopamine receptor agonist, works by imitating the role of dopamine in the brain. It is still unknown what effects long-term use of pergolide may have on patients. Some may develop a tolerance to it. However, researches are encouraged by studies showing that a low dose of pergolide remains effective for a year or more.
The study was sponsored by Eli Lilly, the pharmaceutical company that manufactures pergolide.
