Neurontin: Pfizer and Eli Lilly share a common history

My mother-in-law was telling me yesterday about how her hairdresser’s daughter has been diagnosed bipolar with OCD characteristics. She says her daughter’s on “Neo-something” – she couldn’t quite remember the name.

I racked my brain for a bipolar med name that began with “n.” Nothing really came to mind except for neurontin. I told myself, “No, that can’t be right. Isn’t that associated with VNS?”

Nope; Neurontin really is a medication associated with bipolar disorder. Neurontin’s generic name is gabapentin.

Neurontin (gabapentin)

Gabapentin works similarly to GABA (gamma-aminobutyric acid). GABA  is an “inhibitory neurotransmitter” in the vertebrae central nervous system (CNS). My understanding is that GABA is used for relaxation and sleep:

“It acts as a ‘balancer’ for the brain where excitation of the brain is balanced with inhibition.”

Although gabapentin was initially made to help epilepsy, it’s been used off-label as a pain reliever. According to wikipedia, it is “well tolerated in most patients, has a relatively mild side-effect profile, and passes through the body unmetabolized.”

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.

Who makes neurontin? Parke-Davis, a division of Pfizer (yes, the people who make viagra). Wikipedia cites neurontin as “one of Pfizer’s best sellling drugs” and “one of the 50 most prescribed drugs in the U.S. in 2003.” Although Eli Lilly’s Zyprexa is on everyone’s radar, Pfizer had its own issues with neurontin as well – Parke-Davis marketed off-label uses to doctors. (The NYT’s story on it is still available for free.)

“By some estimates, so-called off-label prescriptions account for roughly 90% of Neurontin sales.” (source: San Francisco Chronicle)

Wikipedia states that off-label prescriptions are legal (I’m not sure that they should be), marketing drugs off-label is NOT. Get this:

In 2004, Warner-Lambert [later acquired by Parke-Davis, which as later acquired by Pfizer] agreed to plead guilty and pay $430 million in fines to settle civil and criminal charges regarding the illegal marketing of Neurontin for off-label purposes, and further legal action is pending. UCSF has archived and studied the documents made public by this case which opens a unique window into pharmaceutical marketing and illegal drug promotion.”

Why all the hullabaloo? Apparently, people who were prescribed gabapentin for bipolar disorder attempted or committed suicide.

To try and clear the air, Pfizer’s tried to distance itself from gabapentin and now uses a structurally-related medicine called pregabalin (Lyrica). Pregabalin is used for symptoms associated with neuropathic pain and epilepsy. In the European Union, it is also approved for generalized anxiety disorder (GAD).

So why beat a dead horse since all this occured from 2002-2004?

Gabapentin is STILL not approved for anything other than epilepsy and postherpetic neuralgia, a painful form of shingles.

Gabapentin’s most common side effects

  • dizziness
  • drowsiness
  • peripheral edema (swelling of extremities)

I don’t know why young children were involved in these clinical trials
(some parents are stupid), but in children ages 3–12, common side
effects included:

  • mild-to-moderate mood swings
  • hostility
  • concentration problems
  • hyperactivity

Adenocarcinoma (a malignant cancer that affects glandular tissue) was
also found as a side effect in rats, however, the evidence for that in
humans remains inconclusive.

This is a particularly long post but seeing as my mother’s hairdresser has a daughter on this medication for off-label use, they probably ought to know more about it than they already do.

“Now you know, now you know.” – Norah Jones, “One Flight Down”

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