Patients prescribed dopamine agonists, a widely used class of drugs for conditions such as Parkinson's disease and restless leg syndrome (RLS), have experienced severe and unexpected side effects, including uncontrollable sexual behaviors, compulsive gambling, and other impulsive activities, according to multiple patient accounts and internal drug company reports reviewed by the BBC.
One drug in particular, Ropinirole, marketed under the brand name Requip by pharmaceutical giant GSK, has been linked to heightened sexual impulses and compulsive behaviors. The drug, prescribed more than 17 million times since 1996, works by mimicking dopamine-a brain chemical responsible for movement and pleasure sensations.
Despite documented cases and internal company research acknowledging these risks as early as 2003, many patients claim they were never warned by their physicians about the potential severity of these side effects. An internal GSK report obtained by the BBC highlighted two particularly troubling cases involving men treated with Ropinirole for Parkinson's. One case involved a 63-year-old man who sexually assaulted a seven-year-old girl after his libido dramatically increased during treatment. According to the report, the man's behavior "resolved" after his medication dosage was reduced.
Patients taking dopamine agonists for restless leg syndrome also reported dramatic and distressing behavioral changes. Claire, who was prescribed Ropinirole following pregnancy-induced RLS, described being overwhelmed by sexual urges about a year after beginning treatment. "There remains an element in your head that knows what you're doing is wrong, but it affects you to the point that you don't know you're doing it," Claire told the BBC, recounting episodes of dangerous sexual behavior. These urges subsided immediately after she stopped the medication.
Sarah, another patient prescribed a dopamine agonist for RLS in her 50s, found herself grappling with sudden compulsive behaviors, including explicit online activities and uncontrollable shopping. Sarah's compulsions led her into a downward spiral of addiction, self-medication with opioids, and ultimately, financial ruin-accumulating approximately $30,000 in debt.
Research suggests these impulse control disorders are not isolated occurrences. Studies estimate that between 13% and 24% of Parkinson's patients on dopamine agonists experience significant impulse-related side effects. The American Academy of Sleep Medicine recommends restricting the use of these drugs to short-term scenarios, such as end-of-life care, due to the severity of potential behavioral disruptions.
GSK faced a class-action lawsuit in 2011 from four Parkinson's sufferers who alleged that the company failed to properly warn patients about these risks. The plaintiffs argued that despite studies linking Ropinirole to impulsive behaviors dating back to 2000, GSK delayed explicit warnings until March 2007. The company settled the lawsuit but denied liability.
Responding to these claims, a GSK spokesperson emphasized that Ropinirole has undergone "extensive clinical trials" and maintains a "well-characterized safety profile." They also stated, "As with all medicines, Requip has potential side effects, and these are clearly stated in the prescribing information."
The prescribing information now includes warnings about "altered or increased sexual interest" and "behavior of significant concern." GSK asserts that their findings from the 2003 internal report were shared promptly with health authorities and incorporated into subsequent updates of the drug's prescribing details.
Yet, many patients maintain their doctors failed to adequately inform them about these risks. Another patient, Sue, said her doctors prescribed a second dopamine agonist without warning her of potential compulsive gambling side effects, resulting in £80,000 of debt.
