'He would have been horrified' - error in drug warnings 'misled' families

Warnings about common medications that can cause impulsive behaviours, such as sex and gambling addictions, are being officially reviewed after BBC News identified an error in drug leaflets.

Side effects of a family of drugs used to treat Parkinson's, Restless Legs Syndrome (RLS) and other conditions have led to huge debts, broken marriages, criminality and suicide, our year-long investigation found. More than 350 affected people have contacted the BBC during that period.

One in six Parkinson's patients taking the drugs are affected by impulse control disorders, the clinical term for these behaviours, according to one study cited as the largest of its kind.

Yet we discovered those side effects are described as "uncommon" in leaflets for one of the drugs, suggesting they only affect fewer than one in a hundred patients.

After being alerted by the BBC, the UK's drug safety regulator said that "an error has been identified" and it would be changing that label to "common".

In response to our findings, the Medicines and Healthcare products Regulatory Agency (MHRA) has also begun reviewing warnings for all eight of these medications, which are known as dopamine agonist drugs.

Boehringer Ingelheim, the developer of Pramipexole - the Parkinson's drug with impulsive behaviours listed as "uncommon" - said the regulator had approved its leaflets and that it was committed to improving patient safety.

Neither it nor the MHRA were able to say how long the error had existed for, but the BBC has discovered its inclusion in a leaflet from 2021 - meaning patients have been misled for at least five years.

The MP who heads the Health Select Committee has told us she "wants answers" from the MHRA and believes it should apologise to 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.

Jane Ryde's husband became addicted to pornography and demanded sex at least three times a day after being prescribed Pramipexole to treat his Parkinson's.

She wasn't warned about these side effects by doctors, but when she read about them in the leaflet, she says she was reassured to see them listed as being "uncommon".

By the time she realised her husband had developed heightened sexual urges, she says he was already benefitting from the drug's ability to tackle the physical symptoms of Parkinson's.

It left her facing a near decade-long "nightmare", enduring her husband's "unrecognisable" behaviour - all while trying to hide it from their children.

At one point, she compiled a diary of her husband's behaviour to show his consultant, but says she was offered no help for her welfare or any advice on changing his medication.

Jane's husband died in 2021. She says the man she knew before he was prescribed the drug would have been "horrified" by his behaviour.

She says it is vital that patients and their families are told just how prevalent these side effects can be, and that it is a "huge scandal" that warnings in her husband's medication leaflet were "misleading".

"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."

Unlike Jane, many of the other people who contacted us over the past year didn't make the connection between impulsive behaviours and these medications - leading to devastating consequences.

The MHRA's action as a result of our investigation means that warnings for all dopamine agonists - prescribed more than 1.5 million times in England alone last year - will be reviewed. As well as Parkinson's and RLS, the drugs are used to treat pituitary gland tumours and some mental health conditions.

The mislabelling we identified in the Pramipexole leaflets contrasts with the findings of a major study from 2010, funded and partly designed by the drug's own manufacturer.

Rather than fewer than 1% of Parkinson's patients developing impulse control disorders, as indicated in current leaflets, the study indicated that about 17% of patients on dopamine agonists were affected.

Some of those who took part were also taking another Parkinson's drug, but 14% of patients on a dopamine agonist alone developed an impulse control disorder, the study found. The charity Parkinson's UK (17%) and the NHS (15%) reference similar figures.

Experts have told the BBC these side effects are under-reported because of the shameful behaviour they can cause.

While an "urge to behave in an unusual way" is cited as "common" in the Pramipexole leaflets, a definition of impulse control disorders that breaks down individual behaviours is listed as "uncommon" specifically for Parkinson's patients.

It is an "under-estimate" to say impulse control disorders affect fewer than 1% of patients in drug leaflets, according to Valerie Voon, who was one of the authors of the 2010 study.

Even individual behaviours, such as compulsive gambling, would be considered "common", says Voon, who is a professor of neuropsychiatry at the University of Cambridge.

The BBC has also found that the presentation of the likelihood of these side effects differs widely between manufacturers' drug leaflets.

British firm GSK doesn't list the frequency of side effects for its drug Ropinirole anywhere. This is because, says the MHRA, data for Ropinirole is only based on individual case reports and so can't be used to calculate overall likelihood.

The impulse control disorders caused by Pramipexole are also listed as "uncommon" for Restless Legs Syndrome (RLS), despite dopamine agonists causing between 6% to 17% of patients to develop them, according to clinical advice on the website of health guidance body NICE.

Such discrepancies are "extremely misleading" and will have "huge significance" for patients, says Dr Andy Berkowski, a neurologist who has co-authored clinical practice guidelines for the treatment of RLS in the US.

Dr Berkowski says 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 also end up being treated with dosages that exceed recommended amounts because these drugs can actually 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."

The government should hold the UK's drugs safety regulator to account over the medication warnings, says Liberal Democrat MP Layla Moran - the chair of the health select committee.

"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 told the BBC it would "rectify the disconnect" in warnings and its "substantial" review of all dopamine agonist drugs would seek advice from independent expert committees.

No medicine is risk-free and these drugs have improved many patients' lives, it said.

The classification of these side effects as "uncommon" for Restless Legs Syndrome was correct, it added.

The MHRA also encouraged patients and healthcare professionals to flag any suspected side effects with these medicines to its Yellow Card scheme, which collates adverse experiences of drugs.

Pramipexole developer, Boehringer Ingelheim, says it follows international guidelines in determining side-effect frequencies, and its leaflets reflect the latest available scientific knowledge at all times.

In a statement it 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."