Lumbar
radiculopathy pain represents a major public health problem, with few effective long-term treatments. Preclinical neuropathic and
postsurgical pain studies implicate the
kinase adenosine monophosphate activated
kinase (AMPK) as a potential pharmacological target for the treatment of
chronic pain conditions.
Metformin, which acts via AMPK, is a safe and clinically available
drug used in the treatment of diabetes. Despite the strong preclinical rationale, the utility of
metformin as a potential
pain therapeutic has not yet been studied in humans. Our objective was to assess whether
metformin is associated with decreased lumbar
radiculopathy pain, in a retrospective chart review. We completed a retrospective chart review of patients who sought care from a university
pain specialist for lumbar
radiculopathy between 2008 and 2011. Patients on
metformin at the time of visit to a university
pain specialist were compared with patients who were not on
metformin. We compared the
pain outcomes in 46 patients on
metformin and 94 patients not taking
metformin therapy. The major finding was that
metformin use was associated with a decrease in the mean of "
pain now," by -1.85 (confidence interval: -3.6 to -0.08) on a 0-10 visual analog scale, using a matched propensity scoring analysis and confirmed using a Bayesian analysis, with a significant mean decrease of -1.36 (credible interval: -2.6 to -0.03). Additionally, patients on
metformin showed a non-statistically significant trend toward decreased
pain on a variety of other
pain descriptors. Our proof-of-concept findings suggest that
metformin use is associated with a decrease in lumbar
radiculopathy pain, providing a rational for larger retrospective trials in different
pain populations and for prospective trials, to test the effectiveness of
metformin in reducing
neuropathic pain.