Neuropathic pain is difficult to diagnose and manage.1 In the past, NSAID was deemed useless in treating neuropathic pain. But in the article entitled “Synergistic symptom-specific effects of ketorolac-tramadol and ketorolac-pregabalin in a rat model of peripheral neuropathy,”2 the authors reported that combining NSAID with a weak opioid and α-2-δ-ligand had produced a profound synergistic analgesic effect for the neuropathic pain. Results provided a new implication for the clinical management of neuropathic pain. Their findings, however, can be modified, at least in part, to be more robust. First, to quantify the stimulation sensitivity, the baseline behavior could have been evaluated before the nerve ligation and those rats exhibiting reduced motor behaviors should be excluded from study. Second, to select appropriate subjects for the study, it was necessary to distinguish between experimental rats that had either well-developed or poorly developed neuropathic pain.3 Because in the rat model of spared nerve injury, pain could have been induced by various factors, and different observation times post ligation could be related to different injury statuses.4 Third, other researchers5 used the placebo group to exclude incidental effects caused by incision trauma or anesthetic agents. Such placebo group could help determining the true effects. Fourth, to mimic the clinical scenario of managing the neuropathic pain, the study analgesic drugs should be injected only after the development of neuropathic pain had been confirmed postoperatively.6 These technical modifications of the experiment can provide more confidence in using NSAIDs to treat neuropathic pain.
1. Teixeira MJ. [Challenges in the treatment of neuropathic pain].Drugs Today (Barc)200945Suppl C)1–5
2. Lin WY, Cheng YT, Huang YH, Lin FS, Sun WZ, Yen CT. Synergistic symptom-specific effects of ketorolac-tramadol and ketorolac-pregabalin in a rat model of peripheral neuropathy.J Chin Med Assoc201982457–63
3. Woolf CJ, Mannion RJ. Neuropathic pain: aetiology, symptoms, mechanisms, and management.Lancet19993531959–64
4. Decosterd I, Woolf CJ. Spared nerve injury: an animal model of persistent peripheral neuropathic pain.Pain200087149–58
5. Dougherty PM, Garrison CJ, Carlton SM. Differential influence of local anesthetic upon two models of experimentally induced peripheral mononeuropathy in the rat.Brain Res1992570109–15
6. Marwa A, Esam M, Awad R, Gamal K, Adel Z. Synergistic efficacy of tramadol and meloxicam on alleviation of pain and selected immunological variables after sciatic nerve ligation in rats.Int J Vet Sci Med2014214–20