• James C Eisenach, Regina S Curry, and Timothy T Houle.
• Department of Anesthesiology, Wake Forest University School of Medicine, Winston Salem, NC 27157, United States.
• Pain Med. 2023 Sep 1; 24 (9): 105810651058-1065.

ObjectiveCompare intrathecal oxytocin, 100 µg to placebo on ongoing neuropathic pain and mechanical hyperalgesia and allodynia.Study DesignRandomized, controlled, double-blind cross-over.SettingClinical research unit.SubjectsIndividuals aged 18 to 70 years with neuropathic pain for at least 6 months.MethodsIndividuals received intrathecal injections of oxytocin and saline, separated by at least 7 days, and ongoing pain in neuropathic area (VAS [visual analog scale]) and areas of hypersensitivity to von Frey filament and cotton wisp brushing were measured for 4 hours. Primary outcome was VAS pain in the first 4 hours after injection, analyzed by linear mixed effects model. Secondary outcomes were verbal pain intensity scores at daily intervals for 7 days and areas of hypersensitivity and elicited pain for 4 hours after injections.ResultsThe study was stopped early after completion of 5 of 40 subjects planned due to slow recruitment and funding limitations. Pain intensity prior to injection was 4.75 ± 0.99 and modeled pain intensity decreased more after oxytocin than placebo to 1.61 ± 0.87 and 2.49 ± 0.87, respectively (P = .003). Daily pain scores were lower in the week following injection of oxytocin than saline (2.53 ± 0.89 vs 3.66 ± 0.89; P = .001). Allodynic area decreased by 11%, but hyperalgesic area increased by 18% after oxytocin compared to placebo. There were no study drug related adverse effects.ConclusionAlthough limited by the small number of subjects studied, oxytocin reduced pain more than placebo in all subjects. Further study of spinal oxytocin in this population is warranted.Trial RegistrationThis study was registered at ClinicalTrials.gov on 03/27/2014 (NCT02100956). The first subject was studied on 06/25/2014.© The Author(s) 2023. Published by Oxford University Press on behalf of the American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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