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Low-Dose Dextromethorphan for the Treatment of Fibromyalgia Pain: Results from a Longitudinal, Single-Blind, Placebo-Controlled Pilot Trial

Authors Mueller C, Ness TJ, Younger JW

Received 8 October 2020

Accepted for publication 26 November 2020

Published 27 January 2021 Volume 2021:14 Pages 189—200


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr E Alfonso Romero-Sandoval

Christina Mueller,1 Timothy J Ness,2 Jarred W Younger1

1Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, USA; 2Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, USA

Correspondence: Jarred W Younger
Department of Psychology, University of Alabama at Birmingham, CH233, 1300 University Blvd, Birmingham, AL 35233, USA
Tel +1 (205) 975-5907
Fax +1 (205) 934-6440

Objective: Fibromyalgia (FM) is a debilitating chronic pain condition with few treatment options. Central sensitization and neuroinflammation have been forwarded as models of FM pathophysiology, both of which indicate dextromethorphan (DXM) as a potential treatment. DXM is an NMDA-receptor antagonist and microglial modulator with anti-neuroinflammatory properties at low doses. It is available for clinical use but has not been tested as a treatment for FM at low dosages. This study evaluated the effectiveness of DXM in treating FM-associated symptoms.
Methods: In a single-blind, placebo-controlled trial, 14 women meeting the 2010 American College of Rheumatology criteria for FM received a placebo for five weeks, followed by 20 mg DXM for ten weeks, while providing daily symptom reports on a 0– 100 scale. Pain and physical activity were the primary and secondary outcomes, respectively. Daily symptom ratings during the last four weeks of placebo were contrasted with ratings during the last four weeks of the active treatment using generalized estimating equations (GEE).
Results: DXM was well tolerated, and treatment adherence was high. Baseline pain was reduced by at least 20% in six participants. Self-reported daily pain and physical activity in the entire cohort were not significantly different between the placebo and DXM conditions, and the primary hypotheses were not supported. Exploratory analyses using the entire placebo and DXM data showed that pain was significantly lower in the DXM condition than in the placebo condition (b=− 9.933, p=0.013).
Discussion: A strong clinical effect of DXM was not observed at the 20mg/day dosage.

Keywords: fibromyalgia, dextromethorphan, clinical trial, neuroinflammation, analgesia

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