Currently, there is lack of evidence to demonstrate that antiepileptic drugs (AEDs) significantly reduce the level of acute pain, myofascial pain, low back pain, or other sources of somatic pain. The evidence of efficacy and safety on AEDs in the treatment of neuropathic pain varies and depends on the specific agent in this drug class.
Neuropathic pain may be defined as pain initiated or caused by a primary lesion or dysfunction in the nervous system, and is characterized by spontaneous pain described as lancinating, paroxysmal, burning, constant, cramping; and evoked pain of dysesthesia, allodynia, hyperalgia, or hyperpathia.
Gabapentin, along with older antiepileptic drugs, may be used as a first line therapy in the treatment of chronic neuropathic pain. Because evidence of efficacy with lamotrigine has been inconsistent and there is no evidence of efficacy and safety for levetiracetam, oxcarbazepine, tiagabine, topiramate, and zonisamide, these drugs will not routinely be covered by the department for the treatment of neuropathic pain. In addition, the Food and Drug Administration (FDA) has recently issued an alert strongly discouraging the off-label use of tiagabine due to a paradoxical occurrence of seizures in patients without epilepsy.
Group 1, Neuropathic Pain Conditions
Gabapentin, and older antiepileptic drugs, are most likely to be effective when prescribed for the following neuropathic pain conditions or diseases that are known to cause neuropathy:
- Diabetic neuropathy
- Post herpetic neuralgia
- Trigeminal neuralgia
- Spinal cord injury
- Cauda equina syndrome
- Phantom limb pain
- Human immunodeficiency virus (HIV) neuropathy
- Cancer
- Traumatic nerve injury
- Chronic radiculopathy confirmed by pain radiating to the extremity in a dermatomal pattern and either objective examination findings of motor, sensory, or reflex changes, or abnormal imaging; or electromyography/nerve conduction velocity EMG/NCV abnormality.
Group 2, Questionable Neuropathic Pain Conditions
Gabapentin is less likely to be effective for questionable neuropathic pain conditions with no objective finding of nerve injury. Use of gabapentin for questionable neuropathic pain conditions should be authorized only after consultation and recommendation from a physician specializing in pain therapies, rehabilitation and physical medicine, anesthesiology, or neurology. It is recommended that a physician specializing in pain therapies have a subspecialty certification in pain medicine from the American Board of Medical Specialties.
Group 3, Non-Neuropathic Pain Conditions
There is no scientific evidence that antiepileptic drugs are effective in treating acute pain, somatic pain from strains or sprains, or myofascial pain. Gabapentin would not be authorized for non-neuropathic pain conditions such as:
- Acute musculoskeletal pain
- Primary somatic pain from chronic musculoskeletal strain/sprain
- Low back pain without radiculopathy
- Tendonitis
- Repetitive strain without evidence of entrapment neuropathy
Recommended Dosing
Refer to the original guideline document for a recommended dosing plan for gabapentin (Neurontin®) in the management of neuropathic pain.
If pain level remains the same, discontinue gabapentin gradually over a one week period. Referral to a pain specialist may also be indicated if there is no improvement in pain level.
