Neurontin has been in use since 1994 for the control of epilepsy. Since 1996 it has been quietly prescribed for many other conditions: such as Reflex Sympathetic Dystrophy (RSD), brain injury, essential tremors, sleep dysfunction, Interstitial Cystitis, agitation secondary to dementia, muscle cramps, TMJ, neuropathic pain, shoulder-hand syndrome, hemifacial spasms, chronic pain, peripheral neuropathy, the pain and spasticity of Multiple Sclerosis (MS), trigeminal neuralgia, migraines, neuropathic pain, acute and postherpetic neuralgia (Shingles), post-operative pain, myofascial pain (MPS), radiation myelopathy, Restless Leg Syndrome (RLS), Lou Gehrig's Disease (ALS), Periodic Leg Movement (PLM).

Gabapentin (Neurontin) represents a novel class of antihyperalgesic agents (pain medications). It also has been shown to be helpful with Bipolar Disorder, social phobias, somatoform pain with depression, mood disorders, and both situational and clinical depression.

Gamma-Aminobutyric acid (GABA) is one of the main inhibitory neurotransmitters of the central nervous system and has some effects on the chemical receptors of nerve cells in common with benzodiazapines and barbituates. Certain of these receptors, when activated, cause a rapid influx of chloride ions into the nerve cell. When that occurs the nerver becomes hyperpolarized and is less able to fire and impulse. Thus the nerves are less irritable. This decreases both seizures and pain impulses.

Gabapentin (1-(aminomethyl)cyclohexanacetic acid) mimics the effects of the naturally occuring GABA by binding to those receptors on the surface of nerve cells that raise the firing threshold. This is believed to be the mechanism by which it inhibits both epileptic siezures and pain.

One study1 looked at the trigger areas in points of the facial skin (allodynia) such as found with trigeminal neuralgia. The results of this study seemed to indicate that the pain was facilitated by a pre-synaptic mechanism. In other words, the pain centers of the brain (particularly in the hippocampus) "learn" to become hypersensitive to stimuli. The pain threshold gets lowered. The conclusion was that Gabapentin (neurontin) was effective in bringing the threshold of stimulation back up to a more normal level.

1. Rev Neurol 1999 Dec 16-31;29(12):1147-53 The effect of gabapentin in bucco-facial allodynia. Experimental correlation of the trigeminal nerve.