The chemical structure of gabapentin is related that of gamma-aminobutyric acid (GABA) which is a neurotransmitter in the brain. The exact mechanism as to how gabapentin controls epilepsy and relieves pain is unknown, but it probably acts like the neurotransmitter GABA.
Animal studies show that gabapentin prevents the development of allodynia (a normally non painful stimulus which is perceived as painful) and hyperalgesia (an exaggerated response to a painful stimulus).
Gabapentin can be very helpful in controlling the pain of trigeminal neuralgia (tic doloreaux), post herpetic neuralgia (the lingering pain after a bout of shingles), the pain of diabetic neuropathy and other neuritic pains such as pain from nerve irritation due spinal arthritis or disc disease and occipital neuralgia. Occasionally it seems to be helpful in controlling migraine and other headaches. It has also been reported to be helpful in controlling the pain of fibromyalgia.
International and domestic studies that have evaluated Neurontin for migraine prevention suggest that it is effective. In a study of 63 patients with migraine (with or without aura), gabapentin significantly reduced migraine frequency and intensity among 30 patients who received it. In this study, adverse events were mild to moderate in severity.
Similarly, in a large study, 143 people with migraine received daily doses of Neurontin or placebo for 12 weeks. At the end of 12 weeks, the migraine rate had declined from 4.2 migraines before treatment to 2.7 migraines after treatment in those who received this drug.
This decrease was significantly greater than the decrease from 4.1 migraines to 3.5 migraines among those who received placebo. Of the 56 gabapentin recipients, 46% had at least a 50% reduction in the four-week migraine rate. Drug-related adverse events (sleepiness and dizziness) led to drug withdrawal in 13% of patients in the gabapentin group compared with 7% in the placebo group. The researchers concluded that this medication is an effective and well-tolerated preventive for migraine.
Gabapentin is an effective prophylactic agent for patients with migraine. In addition, gabapentin appears generally well tolerated with mild to moderate somnolence and dizziness.