#211 Pain getting on your nerves? Tricyclic antidepressants for neuropathic pain
Reading Tools for Practice Article can earn you MainPro+ Credits
Join NowAlready a CFPCLearn Member? Log in
- Systematic review of 10 Randomized Control Trials (RCTs) of amitriptyline involving 588 patients with predominantly diabetic neuropathy (DN) or post herpetic neuralgia (PHN), followed 3-52 weeks:1
- At least moderate (30%) pain relief: 64% versus 32%, Number Needed to Treat (NNT)=4.
- Desipramine and imipramine similar.
- Systematic Review (four amitriptyline RCTs, 384 patients with DN, PHN, mixed neuropathy, followed 4-9 weeks):2
- Inconsistently defined pain relief (examples ³50% pain reduction or patient-reported moderate pain relief): 39% versus 20%, NNT=6.
- At least one adverse effect (six RCTs, 519 patients):
- 55% versus 36%; Number Needed to Harm (NNH)=5.
- Common adverse effects include sedation, dry mouth, vertigo.3,4
- 55% versus 36%; Number Needed to Harm (NNH)=5.
- Withdrawal due to adverse effects (three RCTs, 303 patients):
- 16% versus 7%; NNH=11.
- Other systematic reviews did not provide meta-analyses.5-7 Individual study highlights:
- 30% pain reduction: 40% nortriptyline versus 37% placebo; patient-reported ‘a lot’ of pain relief: desipramine 17-31% versus 4-8% placebo; patient-reported ‘good’ pain relief: imipramine 23% versus 5% placebo.
- Limitations:
- Inconsistent outcome reporting.
- Small study sizes and short duration (may overestimate treatment effect).
- Largest systematic review did not report adverse effects.1
- No adverse effects analysis at varying doses despite wide dose ranges (10-150 mg).5
- Some crossover designs did not use washout period.
- Guidelines8,9 recommend TCAs as a first-line agent for treating neuropathic pain.
- Other treatments for neuropathic pain have similar benefit (NNT of 5-8):
- Gabapentin, pregabalin, serotonin-noradrenaline reuptake inhibitors, tramadol, and opioids.10
- Desipramine and nortriptyline11 may be better tolerated than imipramine and amitriptyline, particularly in geriatrics.12
- TCAs cost ~$25-75 for 90 days (25 mg). Others:13-14
- ~$60 duloxetine, ~$65 gabapentin, ~$110 pregabalin.13
Price differential is important for those with drug coverage