Pain Overview Drug treatment of Neuropathic Pain

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Pain Overview Drug treatment of Neuropathic Pain
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Opioids for neuropathic painEisenberg E, et al.
Cochrane Database of Systematic Reviews 2006,
Issue 3

• Short-term studies provide only equivocal
  evidence regarding the efficacy of opioids
• Intermediate-term studies demonstrate significant
  efficacy of opioids over placebo for neuropathic
  pain, which is likely to be clinically important
• Reported adverse events of opioids are common but
  not life-threatening. Further RCTs are needed to
  establish their long-term efficacy, safety
  (including addiction potential), and effects on
  quality of life

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Antidepressants Saarto T and Wiffen PJ. Cochrane
Database of Systematic Reviews 2005, Issue 3

• Conclusions
• Effect mainly demonstrated in treatment of
  diabetic neuropathy and postherpetic neuralgia
• Benefit is usually seen after a few days
  treatment
• Best evidence available is for amitriptyline
• Usefulness limited by side-effects
• Limited data for the effectiveness of SSRIs
• Advise initiate treatment with amitriptyline and
  switch to an alternative TCA if pain relief
  achieved but side-effects are a problem
• If side-effects still a problem a trial of SSRI
  may yield benefit

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AnticonvulsantsWiffin P, et al. Cochrane Review
Database of Systematic Reviews 2005, Issue 3

• Conclusions
• The type of pain which responds well to
  anticonvulsants is neuropathic pain
• Approximately two-thirds of patients who take
  either carbamazepine or gabapentin can expect to
  achieve good pain relief (but NNTs minor NNHs)
• The evidence here does not support the use of
  anticonvulsants as usual first choice

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Carbamazepine Wiffin PJ, et al. The Cochrane
Database of systematic Reviews 2005, Issue 3

• Twelve RCTs of carbamazepine in neuropathic pain
  (n359)
• Combined NNT for moderate relief in any
  neuropathic pain 2.5 (95 CI 1.8 to 3.8)
• NNH for minor harm 3.7 (95 CI 2.4 to 7.8)
• NNH for major harm not significant
• Concludes
• Use of carbamazepine for neuropathic pain has
  stood the test of time but the evidence is
  limited and of mainly poor quality

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GabapentinWiffin PJ, et al. The Cochrane
Database of systematic Reviews 2005, Issue 3

• Fourteen RCTs of gabapentin in neuropathic pain
  (n1398)
• Combined NNT for improvement 4.4 (95 CI 3.5 to
  5.7)
• NNH for minor harm 3.7 (95 CI 2.4 to 5.4)
• NNH for major harm not significant
• Concludes
• Gabapentin is effective for a variety of
  neuropathic pain, however, needs to be considered
  alongside other treatments such as carbamazepine
  and tricyclic antidepressants (effective and
  affordable alternatives)

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Pregabalin Regional Drug and Therapeutics
Centre. New Drug Evaluation No. 66 November 2004

• Pregabalin is structurally related to gabapentin
  - licenced for peripheral neuropathic pain
• No trials comparing pregabalin with carbamazepine
  or gabapentin
• No evidence patients who fail to respond to
  gabapentin will respond to pregabalin
• Amitriptyline and carbamazepine remain first line
  choices for treatment of neuropathic pain

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Topical Capsaicin Mason L, et al. BMJ 2004 328
9914

• 6 DBRCTs, 656 people, were pooled for neuropathic
  conditions. Relative benefit vs. placebo was 1.4
  (95 CI 1.2 to 1.7), NNT6
• 3 DBRCTs, 368 people, were pooled for
  musculoskeletal conditions. Relative benefit was
  1.5 (1.1 to 2.0), NNT8
• One third of patients on active treatment had
  local adverse reactions
• Although topically applied capsaicin has
  moderate to poor efficacy ..it may be useful
  .for a small number of patients unresponsive to,
  or intolerant of, other treatments.

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Neuropathic Pain- Summary

• If patient has symptoms of neuropathic pain an
  early trial of adjuvant therapy is appropriate
• Most adjuvant drugs are not licensed for this
  indication but this is not a barrier to use
• Best evidence for amitriptyline as first line
  treatment of neuropathic pain
• Best evidence for anticonvulsants is for
  carbamazepine (unlicenced but need not preclude
  use)
• The evidence for gabapentin and pregabalin is
  limited