Drug-Induced Car Crashes? Parkinson’s Disease Drugs and the Risk of Sudden Sleep

Neurologists have known for a while that certain drugs used to treat Parkinson (or Parkinson’s) disease can cause sudden, uncontrollable sleep. But a Harvard Medical School study appearing in the August 2005 Archives of Neurology provides important new data indicating that the risk of sudden sleep is considerable.  

The study quantified the risk of sudden uncontrollable sleep with use of the drugs pergolide (PERMAX), pramipexole (MIRAPEX), and ropinirole (REQUIP). The study found that 22 percent of patients — approximately 1 in 5 — taking these drugs have experienced an episode of uncontrollable sleep.

As a family, these drugs are collectively called dopamine agonists. Dopamine is a chemical transmitter and these drugs appear to work by stimulating dopamine receptors in the brain.    

Case reports and small studies suggested that dopamine agonists may cause uncontrollable sleep. We first wrote about the possibility with pramipexole and ropinirole in the September 1999 issue of Worst Pills, Best Pills News and about pergolide in the February 2004 issue of the newsletter.  

According to the Harvard researchers, this is the largest published study looking at the increased risk of sudden sleep with the dopamine agonists. The researchers identified 929 patients with Parkinson’s disease and conducted a 45- to 60-minute interview covering their drug use, adverse drug reactions, and how their treatment had been going during the preceding six months. The patients’ physicians also participated in the study by doing complete medical record reviews, detailing each patient’s clinical history and the drugs that were prescribed.

The researchers’ primary interest was identifying an episode of sleep that was uncontrollable, severe, and inappropriate, especially while driving or engaged in a social activity.

As mentioned above, 22 percent, or 206 of the 929 patients interviewed, had experienced at least one episode of uncontrollable sleep in the previous six months, in a large number of instances while driving a car. Patients taking pergolide, pramipexole, or ropinirole were nearly three times more likely to have had episodes of uncontrollable sleep than patients using other drugs to treat their Parkinson’s disease. The researchers were also able to determine that as the doses of these drugs increased, so did the risk of uncontrollable sleep.

Among the 206 patients who reported having at least one episode of sudden sleep, 37 percent reported having from one to four episodes and 33 percent reported having 26 or more episodes during the six-month period preceding the interview.   There were 24 patients, or 12 percent, who reported having daily episodes.

Ropinirole was approved by the Food and Drug Administration (FDA) in May 2005 to treat moderate to severe restless leg syndrome in addition to its approved use for Parkinson’s disease. This condition is characterized by an urge to move the legs, usually accompanied by pain or discomfort. These feelings can occur while sitting, lying or sleeping, and are relieved with movement. Patients with this condition frequently have involuntary leg movements during sleep. The symptoms are worse in the evening and at night and can often disrupt sleep.

The Medical Letter on Drugs and Therapeutics, a reference we frequently cite because of its reputation for providing independent drug information to physicians and pharmacists, concluded in its August 2005 review of ropinirole and restless leg syndrome that “It has been modestly effective compared to placebo, but its toxicity may be a problem.”

We will do a more complete critique of ropinirole in the treatment of restless leg syndrome after the FDA releases its reviews of the data submitted to support the approval of the drug for this use.

The possibility clearly exists that sudden uncontrollable sleep will also be experienced by patients using ropinirole for restless leg syndrome. At this time, it is not known if the risk of this adverse drug reaction is higher in patients being treated with this drug for Parkinson’s disease or for restless leg syndrome.

The recent approval of ropinirole for restless leg syndrome will greatly expand the number of people using this drug because many more people have restless leg syndrome than Parkinson’s disease. Of course, the greatest concern is the possibility of suddenly falling asleep while driving or engaging in other activities with a risk of physical harm.

What You Can Do

You should not drive a car or engage in other potentially dangerous activities unless you have gained sufficient experience from taking any of these drugs while engaged in non-dangerous activities to gauge whether or not you are affected adversely.