December 11, 2014

Pfizer Offers Settlement to Parkinsonians Who Developed Sex and Gambling Compulsions

Earlier this week, Pfizer Australia confirmed offering a settlement to 150 people who claim to have developed addictions – especially to gambling and sex – after taking Cabaser (generic cabergoline), a drug for Parkinson’s disease (PD). 

Those individuals – who brought their class action suit in 2008 -- say they were not warned about the possible addictive side effects, for years a connection well-known in the medical literature. The Australian federal court is scheduled to rule on the case next year.

Patients said they’d never had compulsive issues before taking the drug, which is designed to enhance the availability of dopamine, sometimes thought of as a “feel-good” agent in the brain. An excess of dopamine is associated with risk-taking behavior.

Some of the people involved in the suit claim they became gambling addicts and lost hundreds of thousands of dollars after taking the drug. Others developed compulsive sexual or shopping activities. The unusual behaviors typically ceased after patients stopped taking the drug. Of course, discontinuing the drug brought a return of PD’s troubling symptoms... a difficult cycle.

For Years, an Acknowledged Link 
Drug companies and doctors have known for over a decade about the causative link between PD drugs and compulsive behaviors. Interestingly, in 2005 the Parkinson’s Disease Foundation (PDF) posted an article online -- "Gambling, Sex, and…Parkinson's Disease?" -- that suggested gambling and sexual addictions might even be symptoms of the disease itself, not simply a consequence of medications. The PDF also noted that PD meds could exacerbate the problems. Here’s how that article began:
Add impulse-control disorders such as pathological gambling and hypersexuality to the list of possible non-motor problems that can occur in individuals with Parkinson's disease (PD). Recent studies suggest that seriously disabling impulsive behaviors occur in three to five percent of PD patients, affecting individuals at all stages of the disease. The exact prevalence of such disturbances in PD is not entirely clear since the behaviors are often performed in secret, or because the association with PD seems improbable and is therefore never reported at doctor visits.

To further explore the connection between the PD drugs and these compulsive behaviors, researchers at the Institute for Safe Medication Practices in Alexandria, Virginia, analyzed 2.7 million serious drug side effects reported between 2003 and 2012 in the U.S. and 21 other countries. That's an impressive sample.

Dopamine Agonists: Clear Culprit
Of the 1,580 impulse-control-disorder events they identified, 710 of them were linked to dopamine agonist drugs (like Cabaser) and 870 were associated with other drugs. While those dopamine agonists were also occasionally prescribed for Restless Leg Syndrome, they were most often used to treat PD symptoms.

Study lead author Thomas J. Moore reported that dopamine agonists were 277 times more likely to result in a report of specific impulse control symptoms than other drugs. Moore said, “This tells you that reports associating a drug with pathological gambling or hypersexuality are extremely rare, except for this group of drugs.”

Daiga Heisters of Parkinson’s UK, said: 
A significant minority of those taking dopamine medication find they have problems with compulsive behaviour. Every individual reacts differently to Parkinson’s drugs. By talking with their specialist, they can look at altering the dose or drug, and side-effects can be alleviated or even eliminated. It’s important doctors make their patients aware this can happen and monitor them.

Levodopa, Dopamine Agonist... What's the Difference?
Compulsive and impulsive behaviors have also been linked to levadopa therapy – the most common treatment for PD symptoms – but these aberrant activities are most often associated with dopamine agonists. What’s the difference between the two therapies?

The brain converts levodopa into the neurostransmitter dopamine, the depletion of which causes the typical PD symptoms. On the other hand, dopamine agonists help restore dopamine activity in the brain by stimulating the same receptor sites as dopamine, but not by being converted into dopamine.

Dopamine agonists are often used in newly-diagnosed Parkinsonians, and usually those under 60. Taking agonists can delay the use of levodopa and thereby postpone the motor fluctuations that typically develop after long-term levodopa therapy. 

In an article titled "Dopamine Agonists for Early Parkinson Disease," the American Family Physician website put it this way:
According to the American Academy of Neurology, dopamine agonists can be used as an alternative initial therapy and as an adjunct to levodopa to decrease long-term motor complications. This approach is especially desirable in younger patients with mild disease to delay the use of levodopa. However, all patients with Parkinson disease will likely need levodopa at some point.
While levodopa and dopamine agonist therapies bring similar relief for PD symptoms, it’s the agonists that carry by far the greater risk of generating the compulsive behaviors at the center of the class action suit against Pfizer.  

If such a settlement is proposed by BigPharma in Australia, can other continents be far behind?

I can’t blame dopamine agonists for my own sexual compulsions, since I haven't used those drugs. My unusual behavior also began long before my PD diagnosis.

The Next PD Study?
Nonetheless, here’s a question: Do early compulsive behaviors – hypersexuality, gambling, shopping – in any way indicate increased likelihood of developing PD later in life?

No comments: