Official Review of Drug Warnings After Error Identified
Warnings regarding common medications linked to impulsive behaviours, including sex and gambling addictions, are undergoing an official review following the identification of an error in drug leaflets by .
Side effects associated with a group of drugs used to treat Parkinson's disease, Restless Legs Syndrome (RLS), and other conditions have resulted in significant personal and financial harm, including debts, broken marriages, criminal activity, and suicide, according to a year-long investigation by the BBC. Over 350 individuals affected by these side effects have contacted the BBC during this period.
Research indicates that approximately one in six Parkinson's patients taking these medications experience impulse control disorders, the clinical term for such behaviours, according to a major study cited as the largest of its kind.
Despite this, the side effects are described as "uncommon" in the leaflets for one of the drugs, implying they affect fewer than one in a hundred patients.
Following the BBC's alert, the UK's drug safety regulator acknowledged that "an error has been identified" and announced plans to amend the label to classify these side effects as "common".
In response to the findings, the Medicines and Healthcare products Regulatory Agency (MHRA) has initiated a review of warnings for all eight medications in this category, known as dopamine agonist drugs.
Boehringer Ingelheim, the manufacturer of Pramipexole—the Parkinson's drug whose leaflets currently list impulsive behaviours as "uncommon"—stated that the regulator had approved its leaflets and affirmed its commitment to enhancing patient safety.
Neither Boehringer Ingelheim nor the MHRA could specify how long the error had persisted, but the BBC found the incorrect classification present in a leaflet dating back to 2021, indicating that patients have been misled for at least five years.
The chair of the Health Select Committee, MP Layla Moran, has expressed that she "wants answers" from the MHRA and believes the agency should apologise to affected families for the mistake.
"I just can't even begin to imagine hearing what they've been through - abuse, financial ruin, all that you've uncovered - and then to find out that they could have been so much better forewarned," said Layla Moran.
Personal Impact: Jane Ryde's Experience
Jane Ryde's husband developed an addiction to pornography and exhibited a heightened sexual drive, demanding sex at least three times daily after being prescribed Pramipexole for Parkinson's disease.
Jane was not informed of these potential side effects by medical professionals. When she read about them in the medication leaflet, she was reassured by their classification as "uncommon."
By the time Jane recognized her husband's increased sexual urges, he was already benefiting from the drug's effectiveness in managing Parkinson's physical symptoms.
This situation led to nearly a decade-long ordeal for Jane, during which she endured her husband's "unrecognisable" behaviour while trying to shield their children from it.
At one point, Jane maintained a diary documenting her husband's behaviour to present to his consultant, but she reports receiving no support for her own welfare or guidance on adjusting his medication.
Jane's husband passed away in 2021. She believes the man she knew before the medication would have been "horrified" by his subsequent behaviour.
Jane emphasizes the importance of informing patients and families about the true prevalence of these side effects and describes the misleading warnings in her husband's medication leaflet as a "huge scandal."
"You have to go into these things with your eyes open. If you're not given the details, you don't know what to look out for.
If this information could be corrected, it would hopefully stop future husbands, wives, sons, daughters, having to put up with this sort of behaviour."
Wider Consequences and Unrecognized Side Effects
Unlike Jane, many others who contacted the BBC over the past year did not associate their impulsive behaviours with these medications, resulting in severe consequences.
Reports include individuals who developed compulsive gambling and shopping habits, sometimes incurring losses of hundreds of thousands of pounds. One solicitor stole £600,000 from vulnerable clients to fund sex workers, sex-chat sites, and antiques purchases.
The MHRA's response to the investigation includes reviewing warnings for all dopamine agonists, which were prescribed over 1.5 million times in England alone last year. These drugs are also used to treat pituitary gland tumours and certain mental health conditions.
Discrepancies in Side Effect Frequency and Research Findings
The misclassification found in Pramipexole leaflets contrasts with a significant 2010 study, funded and partly designed by the drug's manufacturer.
Instead of fewer than 1% of Parkinson's patients developing impulse control disorders, as suggested in current leaflets, the study found that about 17% of patients on dopamine agonists experienced these disorders.
Some participants were also taking other Parkinson's medications, but 14% of patients on dopamine agonists alone developed impulse control disorders, according to the study. Similar figures are referenced by Parkinson's UK (17%) and the NHS (15%).
Experts have indicated to the BBC that these side effects are under-reported due to the shame associated with the behaviours they provoke.
While an "urge to behave in an unusual way" is classified as "common" in Pramipexole leaflets, the specific definition of impulse control disorders, which details individual behaviours, is listed as "uncommon" for Parkinson's patients.
Valerie Voon, a professor of neuropsychiatry at the University of Cambridge and one of the 2010 study's authors, describes the leaflet's estimate of fewer than 1% as an "under-estimate."
"Even individual behaviours, such as compulsive gambling, would be considered 'common'," said Voon.
Variations in Manufacturer Leaflets and Misleading Information
The BBC also found significant variation in how manufacturers present the likelihood of these side effects in their leaflets.
For example, British pharmaceutical company GSK does not specify the frequency of side effects for its drug Ropinirole, as the MHRA explains that data is based only on individual case reports, making it unsuitable for calculating overall likelihood.
Pramipexole's leaflets also list impulse control disorders as "uncommon" for Restless Legs Syndrome (RLS), despite clinical guidance from the health advisory body NICE indicating that dopamine agonists cause these disorders in 6% to 17% of RLS patients.
Such inconsistencies are described as "extremely misleading" with "huge significance" for patients by Dr Andy Berkowski, a neurologist and co-author of clinical practice guidelines for RLS treatment in the United States.
Dr Berkowski stated, "Prevalence rates of impulsive behaviours should be one of the first things shown in all leaflets because of their potential to 'ruin' lives."
Many RLS patients receive dosages exceeding recommended levels because these drugs can worsen the underlying condition over time, according to consultant neurologist Dr Guy Leschziner.
"Are impulse control disorders very common on very low doses of these drugs? Probably not. Are they a big problem when doses are high? Yes, they are."
Calls for Accountability and Regulatory Response
Liberal Democrat MP Layla Moran, chair of the Health Select Committee, has called for government accountability regarding the MHRA's handling of medication warnings.
"When you've got the MHRA making these kinds of mistakes with the consequences that we've seen for people's lives, I think this is now a case for the government to look at this again."
The MHRA informed the BBC that it would "rectify the disconnect" in warnings and that its "substantial" review of all dopamine agonist drugs would involve consultation with independent expert committees.
The agency acknowledged that no medicine is without risk and noted that these drugs have improved the lives of many patients.
It also stated that the classification of these side effects as "uncommon" for Restless Legs Syndrome was accurate.
The MHRA encouraged patients and healthcare professionals to report any suspected side effects related to these medicines through its Yellow Card scheme, which collects adverse drug experiences.
Manufacturer's Statement on Patient Safety and Awareness
Boehringer Ingelheim, the developer of Pramipexole, stated that it adheres to international guidelines when determining side-effect frequencies and ensures that its leaflets reflect the most current scientific knowledge.
In a statement, the company said:
"Boehringer Ingelheim is aware of some people who have described experiencing impulse control disorders after being prescribed a dopamine agonist for their symptoms of Parkinson's disease or Restless Legs Syndrome. We recognise their courage in talking about these difficult issues and raising awareness."
