Tricyclic antidepressants (TCAs), serotonin-norepinephrine reuptake inhibitors (SNRIs) and anti-epileptic drugs (AEDs) are the mainstays of adjuvant therapy for neuropathic pain. This is a review of the evidence for the use of AEDs in the treatment of neuropathic pain.
Evidence is presented as numbers needed to treat (NNT) and numbers needed to harm (NNH). For instance, an NNT of 5 for 50% pain reduction means for every 5 patients treated with a drug, only 1 of them would achieve a 50% reduction in pain.
The information is based on research conducted in adult patients with chronic pain
is effective in treating central and peripheral neuropathic pain. The effect of gabapentin on chronic neuropathic conditions (including post-herpetic neuralgia, painful diabetic neuropathy, mixed neuropathic pain), the NNT is 5.8 (4.8-7.2) to achieve at least moderate benefit. Adverse effects are frequent, usually tolerable and include drowsiness, dizziness and edema. The dose adjusted for renal dysfunction, and it should be withdrawn gradually to avoid precipitating seizures. Maximum dose is 3,600 mg/day.
is effective in treating peripheral and central neuropathic pain. Its effectiveness increases as the dose approaches 600 mg/day. At this dose, the NNT to decrease pain by 50% for the following conditions is: 3.9 (range 3.1-5.1) for post-herpetic neuralgia; 5.0 (range 4.0-6.6) for diabetic neuropathy; and 5.6 (range 3.5-14) for central neuropathic pain. There are no differences in side-effects between pregabalin and placebo. Dosing starts at 150 mg/day in divided doses either twice or three times daily.
is effective for neuropathic pain, specifically trigeminal neuralgia, but is not considered first-line therapy due to its adverse effects: leukocytosis, thrombocytopenia, dizziness, drowsiness, ataxia, nausea/vomiting and blurred vision - there is also a risk of agranulocytosis, aplastic anemia, and Stevens Johnson syndrome. Dosing starts at 100-200 mg twice a day and is titrated by 200 mg/day every 3 – 5 days until pain relief is achieved. Maximum dose is 1,200 mg/day.
is an analogue of carbamazepine which is equally effective at treating trigeminal neuralgia but with fewer side effects. It can be started at 300 mg twice a day and titrated up by 300 mg/day every 3 days to therapeutic effect. Maximum dose is 2,400 mg/day.
is no recommended as first line therapy. Adverse effects include liver function test abnormalities, dizziness, drowsiness and nausea. Maximum dose is 60 mg/kg/day.
failed to demonstrate efficacy for painful diabetic neuropathy. Serious adverse events include convulsion, bradycardia, syncope, sedation, nausea, diarrhea and metabolic acidosis. Dosing starts at 50 mg/day and can be titrated up to 400 mg/day.
has weak evidence supporting its use. Dosing starts at 50 mg twice daily; abrupt discontinuation can precipitate seizures.
See reference for more information.
Adapted from Hepner S, Claxton R. Anti-epileptic drugs for pain. Palliative Care Network of Wisconsin. Fast facts and concepts #271. Internet. Accessed on December 27, 2018.