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Pain Research and Treatment
Volume 2012, Article ID 150842, 12 pages
http://dx.doi.org/10.1155/2012/150842
Research Article

Morphine and Clonidine Synergize to Ameliorate Low Back Pain in Mice

Maral Tajerian,1,2,3 Magali Millecamps,1,2,4 and Laura S. Stone1,2,3,4,5,6

1Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada H3G 0G1
2McGill Scoliosis & Spine Research Group, McGill University, Montreal, QC, Canada H3A 2B4
3Department of Neurology & Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada H3A 3R8
4Faculty of Dentistry, McGill University, Montreal, QC, Canada H3G 0G1
5Department of Anesthesia, Faculty of Medicine, McGill University, Montreal, QC, Canada H3G 1Y6
6Department of Pharmacology & Therapeutics, Faculty of Medicine, McGill University, Montreal, QC, Canada H3G 1Y6

Received 2 December 2011; Revised 28 January 2012; Accepted 4 February 2012

Academic Editor: María Asunción Romero Molina

Copyright © 2012 Maral Tajerian et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Chronic low back pain (LBP) is a debilitating condition associated with signs of axial and radiating pain. In humans with chronic LBP, opioids are often prescribed with varying outcomes and a multitude of side effects. Combination therapies, in which multiple pharmacological agents synergize to ameliorate pain without similar potentiation of adverse reactions, may be useful in improving therapeutic outcome in these patients. The SPARC-null mouse model of low back pain due to disc degeneration was used to assess the effects of opioid (morphine) and -adrenergic agonist (clonidine) coadministration on measures of axial and radiating pain. The results indicate that systemic morphine and clonidine, coadministered at a fixed dose of 100 : 1 (morphine : clonidine), show a synergistic interaction in reversing signs of axial LBP, in addition to improving the therapeutic window for radiating LBP. Furthermore, these improvements were observed in the absence of synergy in assays of motor function which are indicative of side effects such as sedation and motor incoordination. These data show that the addition of low-dose systemic clonidine improves therapeutic outcome in measures of both axial and radiating pain. Combination therapy could be of enormous benefit to patients suffering from chronic LBP.