Neurontin 0, Placebo 1. Pfizer loses, Placebo wins.

Stephany at soulful sepulcher has a post up on how Neurontin has not shown itself to be more effective for bipolar disorder than placebo in clinical trials.

It's actually kind of funny that this discovery has been made in April 2008 because I'd reported on this back in January of 2007:

So let's recap: gabapentin is FDA-approved for epilepsy ONLY. But gabapentin has a slew of off-label uses.

Don't know what off-label means? It means "not FDA-approved to be prescribed for this use."

Now that we've got that out of the way, gabapentin is prescribed off-label for migraines, bipolar disorder, social anxiety disorder, OCD, treatment-resistant depression, insomnia, multiple sclerosis, neuropathic pain, and in some instances, post-operative chronic pain.

Where did this off-label usage come from? Basically, one journal article published data on beneficial effects for patients on Neurontin for bipolar disorder and then other articles would cite that article as supporting evidence then more articles cited all the other articles that published the positive efficacy data on the drug, creating what UNC researcher Tim Carey calls the "echo chamber effect."  From Fierce Pharma:

Hearing it over and over, doctors were led to believe that Neurontin worked for bipolar patients, and prescribed it to lots and lots of them.

These articles that touted the benefits of Neurontin were cited 400 times. Carey:

It “becomes a rumor mill in which physicians may be exposed to these types of articles, and citations of articles, which then gives credibility to off-label use.”

The conclusion?

“No scientifically acceptable clinical trial evidence supports use” of the drug in bipolar disorder.

Ouch. Hitting Pfizer where it hurts.