Report Ties Parkinson's Drugs to Gambling
Mayo Clinic Doctors Report 11 Cases in Medical Journal
July 12, 2005 -- Mayo Clinic doctors report that certain drugs for Parkinson's disease may have a rare side effect: problem gambling.
M. Leann Dodd, MD, and colleagues outline the possible connection in the Archives of Neurology.
"Pathological gambling is a rare potential complication related to treatment of Parkinson's disease," write the doctors. "However, its [cause] is poorly understood."
Possible Link Not Proven
The doctors didn't test the drugs directly.
Instead, they describe pathological gambling in 11 Parkinson's patients who were taking medications to treat the brain condition.
Parkinson's disease causes dopamine-producing nerve cells to die, and as a result, body movements are affected. The medications restore or improve the level of dopamine in areas of the brain affected by the disease.
For eight of the patients, the gambling "resolved" when the Parkinson's medication was tapered or stopped. The doctors weren't able to follow up with the other three patients.
About Dopamine and the Drugs
Dopamine is made by the brain to help direct movement.
Dopamine also plays a role in the brain's reward and reinforcement system. It "has been implicated in mediating the reward of gambling behavior," write Dodd and colleagues.
Medications used to treat Parkinson's disease act like dopamine. They're taken to help cut Parkinson's symptoms.
"These 11 patients developed pathological gambling only after starting therapy with a dopamine agonist [dopamine-like medication]," write the doctors.
Nine out of the 11 patients were taking Mirapex. The other two were taking Requip.
However, "All of the commonly prescribed dopamine agonists have been associated with pathological gambling," write the doctors.
Mirapex is made by Boehringer Ingelheim Pharmaceuticals. Requip is made by GlaxoSmithKline, a WebMD sponsor.
WebMD contacted both companies for comment.
Boehringer Ingelheim's Response
Boehringer Ingelheim Public Relations Director Kate O'Connor tells WebMD the company doesn't have any specific comments on the report.
Postmarketing reports of "compulsive behaviors (sexual and pathological gambling)" are noted in Mirapex's prescribing information.
That doesn't prove that the drug was responsible for such problems, which the prescribing information points out.
"We proactively made the change to our label in the interest of sharing that information [with] doctors, patients, and physicians," says O'Connor. The change was made in late 2004, she says.