Published Online 15 Oct 2019 | https://doi.org/10.2217/pmt-2019-0032
The effectiveness of ketamine in treating chronic neuropathic pain, however, remains a debated issue. A recent meta-analysis of double blind randomized controlled trials (DB-RCT) utilizing ketamine for chronic neuropathic pain revealed mixed results. Six studies were included in their analysis, with total 99 subjects in the ketamine group and 96 in the placebo group. Intravenous (iv.) equivalent daily dosing ranged from 18 to 480 mg, and treatment length 1 to 90 days. 20 patients had spinal cord injuries, 18 had vascular ischemic pain, 39 had complex regional pain syndrome (CRPS), and 22 had neuropathic pain not defined. Five of the six trials administered ketamine for less than 11 days, while one trial administered ketamine over 90 days. The meta-analysis did not show a reduction in pain intensity at 4 weeks compared with placebo (mean difference [MD] -1.12, 95%; confidence interval [CI] -2.33–0.09). Despite failing to reach their primary end point of pain reduction at 4 weeks, they did find significantly decreased pain intensity at 1, 2, 8 and 12 weeks. Of note, there was a statistically significant increase in psychedelic complications with ketamine use (relative risk [RR] = 5.35 [2.64, 10.81]).
Keywords: ketamine, chronic pain, complex regional pain syndrome