Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/72969
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Type: Journal article
Title: The effects of pregabalin and the glial attenuator minocycline on the response to intradermal capsaicin in patients with unilateral sciatica
Author: Sumracki, N.
Hutchinson, M.
Gentgall, M.
Briggs, N.
Williams, D.
Rolan, P.
Citation: PLoS One, 2012; 7(6):1-8
Publisher: Public Library of Science
Issue Date: 2012
ISSN: 1932-6203
1932-6203
Statement of
Responsibility: 
Nicole M. Sumracki, Mark R. Hutchinson, Melanie Gentgall, Nancy Briggs, Desmond B. Williams and Paul Rolan
Abstract: BACKGROUND: Patients with unilateral sciatica have heightened responses to intradermal capsaicin compared to pain-free volunteers. No studies have investigated whether this pain model can screen for novel anti-neuropathic agents in patients with pre-existing neuropathic pain syndromes. AIM: This study compared the effects of pregabalin (300 mg) and the tetracycline antibiotic and glial attenuator minocycline (400 mg) on capsaicin-induced spontaneous pain, flare, allodynia and hyperalgesia in patients with unilateral sciatica on both their affected and unaffected leg. METHODS/RESULTS: Eighteen patients with unilateral sciatica completed this randomised, double-blind, placebo-controlled, three-way cross-over study. Participants received a 10 mg dose of capsaicin into the middle section of their calf on both their affected and unaffected leg, separated by an interval of 75 min. Capsaicin-induced spontaneous pain, flare, allodynia and hyperalgesia were recorded pre-injection and at 5, 20, 40, 60 and 90 min post-injection. Minocycline tended to reduce precapsaicin injection values of hyperalgesia in the affected leg by 28% (95% CI 0% to 56%). The area under the effect time curves for capsaicin-induced spontaneous pain, flare, allodynia and hyperalgesia were not affected by either treatment compared to placebo. Significant limb differences were observed for flare (AUC) (-38% in affected leg, 95% CI for difference -19% to -52%). Both hand dominance and sex were significant covariates of response to capsaicin. CONCLUSIONS: It cannot be concluded that minocycline is unsuitable for further evaluation as an anti-neuropathic pain drug as pregabalin, our positive control, failed to reduce capsaicin-induced neuropathic pain. However, the anti-hyperalgesic effect of minocycline observed pre-capsaicin injection is promising pilot information to support ongoing research into glialmediated treatments for neuropathic pain. The differences in flare response between limbs may represent a useful biomarker to further investigate neuropathic pain. Inclusion of a positive control is imperative for the assessment of novel therapies for neuropathic pain.
Keywords: Humans; Pain; Sciatica; Hyperalgesia; gamma-Aminobutyric Acid; Capsaicin; Minocycline; Treatment Outcome; Drug Therapy, Combination; Injections, Intradermal; Analysis of Variance; Cross-Over Studies; Double-Blind Method; Time Factors; Adult; Middle Aged; Female; Male
Rights: Copyright: © 2012 Sumracki et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
RMID: 0020119709
DOI: 10.1371/journal.pone.0038525
Appears in Collections:Pharmacology publications

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