Pharmaceutical giant Pfizer has been ordered to pay $142 million US in damages for fraudulently marketing gabapentin, an anti-seizure drug marketed under the name Neurontin.

A federal jury in Boston ruled Thursday that Pfizer fraudulently marketed the drug and promoted it for unapproved uses. The jury sided with California-based Kaiser Foundation Health Plan Inc. and Kaiser Foundation Hospitals, the first to try a gabapentin case against Pfizer.

Data revealed in a string of U.S. lawsuits indicates the drug was promoted by the drug company as a treatment for pain, migraines and bipolar disorder — even though it wasn't effective in treating these conditions and was actually toxic in certain cases, according to the Therapautics Initiative, an independent drug research group at the University of British Columbia.

The trials forced the company to release all of its studies on the drug, including the ones it kept hidden.

A new analysis of those unpublished trials by the Therapeutics Initiative suggests that gabapentin works for one out of every six or eight people who use it, at best. The review also concluded that one in eight people had an adverse reaction to the drug.

"The much larger majority of people will not get any benefit and many of them will have chronic neurotoxicity or poisoning of the brain," said Dr. Tom Perry of the Therapeutics Initiative.

Dr. Harry Pollett, a pain specialist in North Sydney, N.S., calls gabapentin a so-so drug with potentially serious side-effects for patients. These include drowsiness, balance problems, fogginess and edema, or swelling.

"Weight gain is a very common problem and I see that a lot," Pollett said.

The drugs represent a waste of money for Canada's health-care system, said Perry, who questioned why some doctors continue to encourage people to take the drug even though the patients are not benefiting.

"We have been using probably somewhere in the order of around $300 million a year in Canada recently and this drug has been overused since the late 1990s," Perry said. "So, do the math. It's probably well in excess of a billion dollars."

Pfizer defends its actions and its drug. The company has already been hit with $430 million in penalties and fines for fraudulently promoting gabapentin in the U.S.

With files from the Associated Press