Efficacy of intravenous ketamine for neuropathic pain: a systematic review and meta-analysis of randomized clinical trials.
Márcio José Leão Nunes Filho, Eduardo Silva Reis Barreto, Cesar Romero Antunes Júnior et al.
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In 30 seconds
This systematic review and meta-analysis assessed intravenous ketamine versus placebo for chronic neuropathic pain in adults. Fifteen randomized clinical trials involving 251 participants were reviewed; six trials with 135 participants contributed to the primary meta-analysis. Ketamine increased the likelihood of achieving at least a 50% reduction in pain intensity compared with placebo (RR = 2.79, 95% CI: 1.47-5.30). Adverse effects were also more frequent with ketamine. The authors describe the pain relief as potentially effective in the short term, while noting that small samples and methodological heterogeneity limit generalizability.
Key findings
- Across six trials (n = 135), ketamine increased the likelihood of ≥50% pain reduction versus placebo (RR = 2.79, 95% CI: 1.47-5.30; I 2 = 28.3%).
- In studies using a standardized dose of 400 µg/kg, the estimated effect was larger (RR = 5.68; 95% CI: 2.02-15.99; I 2 = 0%).
- Adverse effects were more frequent with ketamine than placebo (RR = 3.27; 95% CI: 2.20-4.84; I 2 = 20.1%); the abstract describes them as generally mild and transient.
Why it matters
The pooled results suggest intravenous ketamine may provide short-term pain relief for adults with chronic neuropathic pain, while also increasing adverse effects. This balance is relevant when weighing potential benefit against tolerability. The evidence remains uncertain in its broader applicability because the included trials were small and methodologically heterogeneous.
What to keep in mind
The authors identify small sample sizes and methodological heterogeneity as limits to generalizability; the primary outcome meta-analysis included six trials and 135 participants.