This article is in our series on Medications for Pain…  what are your choices?  how do various medications work?  what are the pros and cons?  how about side effects?

The class of medication we’re looking at today is called Anticonvulsants, which are medications originally used to treat seizure disorders.  Within this class, there are:

1. “1st generation” anticonvulsants, which are simply older medications.  Tegretol and Dilantin are in this group.
2. “2nd generation” anticonvulsants, which are simply newer medications.  Medications such as Neurontin, Lyrica, and Topamax are in this group.

Effect of Anticonvulsants:  Anticonvulsants work by decreasing the hyper-excitability of nerves, and so decrease how easily pain signals are transmitted.

Uses of Anticonvulsants:  Because anticonvulsants work by slowing down nerve signals, they’re helpful in disorders that have overly-excited nerves.  So they work best in “nerve pain,” which is called neuropathic pain.  They don’t work as well in other pain disorders, for example pain caused by inflammation.

“Neuropathic pain” is pain caused by problems in the nerves running through the body (“peripheral” nerves), or in the brain or spinal cord.  Some examples would be:

• Pain after amputation – nerves are cut and damaged with surgery
• Spinal problems, such as herniated disks – pieces of spine are pushing on nerves as they leave the spinal cord
• Microscopic damage to nerves in the body, such as occurs in diabetes (called diabetic peripheral neuropathy) or shingles (called post-herpetic neuralgia)

What’s most interesting about anticonvulsants is that they work in disorders where we might not expect them to work.  An example is fibromyalgia, which used to be thought of as an inflammatory disorder, or even a psychological disorder.  But anticonvulsants help in fibromyalgia!  What this tells us is that fibromyalgia is, at least partly, neuropathic pain.  This is an important advance, not just in treating fibro, but in understanding other pain disorders.

We now also know that there are changes in the brains of patients with fibromyalgia that make them more likely to experience pain.  So recent brain studies confirm what responding to anticonvulsants suggests – this disorder is partly neuropathic.  Pretty neat convergence of brain studies and medication response!

What medications work?  Some examples of FDA-approved medications:

• Lyrica in diabetic neuropathy and fibromyalgia
• Neurontin in shingles (post-herpetic neuralgia)
• Tegretol in trigeminal neuralgia

Medical Studies:  Anticonvulsants are pretty well studied in various pain disorders, and they help in a wide range of disorders.  What’s important to remember is that only some medications have been studied in some disorders, and have been FDA-approved.  But that doesn’t mean that a medication won’t be helpful for a disorder it’s not formally approved for – for example, Lyrica may help in shingles.  It just may not have been studied yet.  (Click here for a discussion on FDA-approved medications versus “just guessing”.)

Your doctor should tell you if a medication she’s recommending is FDA-approved or not, and if not, how much it’s been studied for your disorder.

Side Effects:

• sedation (which can be helpful for sleep)
• tissue swelling
• weight gain
• cognitive interference – some patients call this “Neurontin head”
• 1st generation anticonvulsants can have more serious side effects, including effects on blood cells.

Anticonvulsants should not be stopped quickly, as this, though rare, can cause seizures.
Read more at http://www.howtocopewithpain.org/blog/3090/anticonvulsants-for-pain-2010/#Q9m4XqYYd4KBwZ6q.99