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with placebo was 3.7 (CI 2.4 to 7.8); the NNH for a major adverse event was insignificant
(Wiffen, McQuay & Moore, 2005 Level I).
Phenytoin
A review of phenytoin for the treatment of chronic neuropathic pain calculated a NNT of 2.1
(CI 1.5 to 3.6) for painful diabetic neuropathy. The NNH for a minor adverse effect compared
with placebo was 3.2 (CI 2.1 to 6.3); the NNH for a major adverse event was not significant
(Wiffen, Collins et al, 2005 Level I).
Gabapentin
A review of gabapentin for the treatment of chronic neuropathic pain calculated a NNT of 4.3
(CI 3.5 to 5.7) overall; the NNTs for painful diabetic neuropathy and postherpetic neuralgia
were 2.9 (CI 2.2 to 4.3) and 3.9 (CI 3 to 5.7) respectively (Wiffen, McQuay, Edwards et al, 2005
Level I). The NNH for a minor adverse effects compared with a placebo was 3.7 (CI 2.4 to 5.4);
the NNH for a major adverse event was not significant. Gabapentin was effective in the
treatment of phantom limb pain (Bone et al, 2002 Level I) and smaller later trials support the
effectiveness of gabapentin in the treatment of central pain after spinal cord injury (Levendoglu
et al, 2004 Level II; Tai et al, 2002 Level II).
Pregabalin
CHAPTER 4 al, 2008 Level I; Gutierrez‐Alvarez et al, 2007 Level I) with an NNT of 3.24 (Gutierrez‐Alvarez et al, 2007
Pregabalin was effective for the management of pain related to diabetic neuropathy (Hurley et
Level I) and an increased risk of sedation and dizziness (Hurley et al, 2008 Level I). Pregabalin was
effective for persistent neuropathic spinal cord injury pain (Siddall et al, 2006 Level II).
Sodium valproate
Sodium valproate was effective for the prevention of migraine (Mulleners & Chronicle, 2008
Level I) but ineffective in the treatment of spinal cord injury pain (Drewes et al, 1994 Level II).
Lamotrigine
A review of lamotrigine concluded that it was unlikely to be of benefit for the treatment of
neuropathic pain (Wiffen & Rees, 2007 Level I).
Key messages
1. Gabapentin is effective in the treatment of chronic neuropathic pain (Q); lamotrigine is
most likely ineffective (N) (Level I [Cochrane Review]).
2. Carbamazepine is effective in the treatment of trigeminal neuralgia (N) (Level I [Cochrane
Review]).
3. Pregabalin is effective in the treatment of chronic neuropathic pain related to diabetic
neuropathy (N) (Level I).
4. Perioperative gabapentinoids (gabapentin/ pregabalin) reduce postoperative pain and
opioid requirements (U) and reduce the incidence of vomiting, pruritus and urinary
retention, but increase the risk of sedation (N) (Level I).
The following tick box represents conclusions based on clinical experience and expert
opinion.
Based on the experience in chronic neuropathic pain states, it would seem reasonable to
use anticonvulsants in the management of acute neuropathic pain (U).
90 Acute Pain Management: Scientific Evidence
