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Max Wells was a wealthy physician who enjoyed trips to Las Vegas for nearly 30 years before he was diagnosed with Parkinson’s disease. As his neurological disease progressed, Wells retired and sold his pathology clinic but continued his gambling trips.

The Texas millionaire claims he had always kept his gambling losses under control. But after he was diagnosed in 2000, he began gambling away hundreds of thousands of dollars.

In 2000, he began taking Mirapex, a “dopamine agonist” that stimulates the dopamine receptors in the brain to alleviate the tremors and other symptoms of Parkinson’s. In consultation with his doctor, Wells stopped taking that drug in 2004 after he read an article warning that Mirapex might cause problem gambling. At that point, Wells had already lost about $2 million gambling.

In October 2004 his doctor prescribed an alternative dopamine agonist, Requip. Requip’s label at the time did not warn of any side effects related to gambling. According to Wells, his gambling urges subsided temporarily but soon returned with a vengeance. From September 2005, when he received the final proceeds from the sale of his clinic, until January 2006, Wells surrendered another $10 million to the Nevada gaming tables–including $4 million in the final month.

At that point he told his doctor about his gambling problem, stopped taking Requip and has not been back to Vegas.

One month later, Wells filed a lawsuit against Requip’s maker, GlaxoSmithKline (GSK), contending that the pharmaceutical giant failed to warn patients that its drug could trigger “an irresistible gambling compulsion” in some people.

The 5th Circuit, however, recently agreed with the U.S. District Court for the Western District of Texas in Wells v. SmithKline Beecham Corp. that GSK was entitled to summary judgment. Expert testimony that Requip could cause compulsive gambling in the general population “did not pass scientific muster,” the 5th Circuit held in its March 22 ruling.

“Because the experts’ opinions are not scientifically reliable, the testimony is inadmissible–leaving the liability cupboard bare,” the court ruled.

Impulse Control

“Pathological” gambling is on a growing list of so-called “impulse control disorders” that plaintiffs are claiming as prescription drug side-effects in product liability suits. Plaintiffs variously contend that drugs have caused them to compulsively eat, drink and shop, take illicit drugs, or turned them into sex addicts. Even a single plaintiff’s damages claim can run into the millions. Class claims ratchet up the stakes. Mirapex, for example, is the subject of a multidistrict litigation action in Minnesota and a Canadian class action which allege the drug can cause compulsive behaviors, including pathological gambling.

Plaintiffs are “trying to broaden the scope of traditional product liability into rather untraditional types of claims such as behavioral disorders,” says Philadelphia defense litigator James M. Beck, author of the Drug and Device Law Blog.

Cases alleging adverse behavioral side effects such as hyper-sexuality or compulsive shopping may be particularly susceptible to pre-trial attacks on the scientific reliability of the plaintiff’s causation evidence, says Dechert Partner Sean Wajert, co-chair of the firm’s pharmaceutical, mass tort and product liability practice group.

“Where the behavior is something that is very amorphous and hard to define and is something that is found in the general population very widely … it’s going to be an uphill battle [for the plaintiff] because you are just not going to be able to get the data,” Wajert predicts.

Failed Experts

That was Wells’ problem. GSK successfully argued that the expert evidence purporting to show that Requip can cause pathological gambling failed the test for admissibility set by Daubert v. Merrell Dow Pharms., Inc., which requires expert evidence to be both reliable and relevant.

Wells’ three experts pointed to published articles documenting case-specific correlations between Requip and gambling; GSK’s internal data purportedly revealing case-specific associations between Requip and gambling; one unpublished study showing a nexus between gambling and Parkinson’s medicines generally; and GSK’s addition of a warning about possible gambling side effects to Requip’s label.

Crucially each of the experts conceded there was no scientifically reliable evidence of a cause-and-effect relationship between Requip and pathological gambling.

“These admissions drain the expert opinions of probative force,” Judge Patrick Higginbotham wrote. He said scientific literature the experts claimed showed “an association” between Requip and problem gambling didn’t represent “scientific knowledge.”

“The bases for the experts’ conclusions pass none of the applicable Daubert tests,” he explained. “That Requip causes problem gambling is not generally accepted, has not been subjected to peer review and publication, and is not backed by studies meeting requisite scientific standards. Without the expert testimony, Wells cannot prove general causation, and judgment must be entered for GSK.”

Kendall Gray, a partner at Andrews Kurth in Houston, says excessive gambling and other destructive behaviors are hard to quantify in studies.

“These cases will continue to be difficult to pursue because the disorders are difficult to define, and the notions of what caused them are imprecise and difficult to establish with any scientific certainty.”