A UBC drug-research group has issued a “therapeutics letter” concluding that a widely used pain reliever has very little effect. The Therapeutics Initiative, which is funded by the B.C. Ministry of Health through a grant to UBC, states in its public letter that gabapentin has a “minor role in pain control”. The letter also claims that misleading promotion pushed this drug to “blockbuster status”.

Gabapentin was originally sold under the name Neurontin, which is a Pfizer medication licensed in Canada in 1993 as an add-on therapy for epilepsy. According to the Therapeutics Initiative letter, U.S. sales reached $2.7 billion per year by 2003 after being marketed “for everything”. Last year, B.C. consumers and the PharmaCare program spent more than $30 million on the drug, with 63 percent coming from public funds.

In a phone interview with the Georgia Straight, Dr. Tom Perry said that after Pfizer’s patent expired in Canada and the United States earlier this decade, generic drug manufacturers began producing their own gabapentin.

Perry, a pharmacologist and chair of the Therapeutics Initiative education working group, noted that brand-name Neurontin still exists, but he doubts many people are buying it, because the generic drug is less expensive.

“The message of the letter is that patients who are taking the drug and doctors who are prescribing it should reassess what they’re doing,” Perry said. “If the patient is getting clear benefit, it’s a relatively safe drug—gabapentin. If they’re not getting benefit, they never will because it doesn’t get better over time.”

According to the letter, about 15 percent of patients receive benefits in reducing neuropathic pain by less than one on a scale of zero to 10. A similar percentage of people suffer harm, the letter adds, noting that opioids “afford greater relief in chronic neuropathic pain, with qualitatively different adverse effects”.

Pfizer has a newer drug called pregabalin. The Therapeutics Initiative says its benefits and harms are similar to gabapentin, but at a higher cost.

Perry noted that most people who take gabapentin for pain relief are probably not receiving any benefit. In addition, Perry said, they are likely to be experiencing some brain toxicity, which often takes the form of somnolence, a mild balance disturbance, mild nausea, or generally impaired thinking.

“It can be surprisingly subtle [in] that people feel they have trouble coming up with the right word,” he said. “They attribute their impaired thinking to something else that happened to them, like a motor-vehicle accident or an underlying condition, like MS [multiple sclerosis].”

However, Perry noted that some people suffer a “very, very profound toxicity” from the drug, which can lead to nausea or major speech disturbances that could be similar to those of stroke victims. In rare cases, he said, people develop psychotic hallucinations. “But usually, it’s more subtle,” he said. “The other thing it tends to do is it causes swelling of the feet, or edema, which patients and doctors never seem to attribute to the drug. That could be risky because people may be diagnosed as having heart failure. They end up being put on a diuretic.”

Perry said he was paid to testify for the plaintiff in a class-action lawsuit against Pfizer in Boston. The Therapeutics Initiative conducted its review of gabapentin by examining unreleased company-financed studies, which were disclosed in the court case.

“Another important lesson from this and similar stories [is] if we really want to protect the public, we need universal access within a reasonable amount of time to all data from clinical trials,” Perry said.

Pfizer Canada did not provide a spokesperson to be interviewed by the Straight. In an e-mailed statement, the company described Neurontin is an “important” Health Canada– and Food and Drug Administration–approved medicine that physicians have prescribed to millions of patients safely and effectively. In addition, the company claimed that this drug has “been widely studied for more than two decades and there is an extensive body of publicly available literature on its safety and its use”.

Perry said that Health Canada will approve a drug if a manufacturer can demonstrate that it’s better than a placebo for a certain condition, and if it’s not horrendously dangerous over the short term. “We have no long-term safety-data requirements for anything, really,” he noted. “Until we get reform of drug licensing and supervision of drugs and other technologies globally, we’re going to continue wasting billions of dollars per year in a country like Canada, and causing a lot of harm to people that could be avoided.”

Related article: The pill pushers

Follow Charlie Smith on Twitter at twitter.com/csmithstraight.