DrugBuyers.Com: new chronic pain med

Gabitril and Neurontin are 2 very different animals, and act by different mechanisms but achieve the same overall outcome - neuronal inhibition.

Gabitril acts by inhibiting reuptake of the inhibitory neurotransmitter GABA, which means more of it is left in the synapse, thereby increasing its efficacy. GABA is a neurotransmitter that acts specifically to reduce the activity of neurons. Its anticonvulsant activity would be mediated that way.

Neurontin (gabapentin) was designed to be a GABA-like drug, but doesn't act at all that way (the best laid plans of mice and men...) It quiets neurons, but by inhibiting calcium channels, and is also an anti-convulsant. These types of drugs are not generally good for acute pain, or pain after surgery, dental procedures, etc. They do work, and sometimes very well, for others not so well, against neuropathic pain. Intense, abnormal pain due to nerve injury by traction, disease (e.g., AIDS, diabetes) or cancer chemotherapy (taxol, vincristine do this) is sometimes treated very well with neurontin or other anticonvulsants. I believe neurontin is approved for neuropathic pain now, but not for other types of pain.

Off-label use of anticonvulsants as an adjunct to other drugs, like opiates, is a common practice against neuropathic pain. Prescribing off-label is not illegal, and not against good medical practice. It is using a drug for a purpose that the FDA did not yet get around to give its blessing. Every indication for a drug has to be approved by lots of testing and paperwork. Fortunately for us, medical science moves much faster than government beaurocrats, and new uses become common knowledge in the scientific and medical communities before the approval process gets underway.

What happens with chronic pain is that neurochemical changes occur in the brain and spinal cord so that neurons of the spinal cord become very sensitized to painful stimuli, which is why it appears so intense. Inflammatory pain, which can include types of arthritis, is well treated by opiates, neuropathic pain is usually not - they involve different neurochemical changes but still cause a sensitized nervous system. The anticonvulsants quite down the sensitized spinal cord, and may alleviate some of the abnormal intense pain, and may act with opioids to bring a synergy in terms of pain relief.

Examples of neuropathic pain states include: nerve injury, amputation, HIV-related, diabetic neuropathy, post-herpetic neuralgia, tic doleroux (trigeminal neuralgia), reflex sympathetic dystrophy (RSD). Tough to treat, and everyone responds differently.

BTW - the benzodiazepines also act through the GABA system, and you surely know they are worthless against pain alone. This is also why WD from benzos can include seizures and is potentially life-threatening.