Clinical trials of the efficacy of antidepressant drugs in patients with chronic low back pain have had mixed results, possibly because of the different mechanisms of action of the drugs that have been studied. Because bupropion has a mechanism of action that differs from other antidepressants and has shown efficacy in neuropathic pain, a randomized, placebo-controlled, 2-period crossover trial was conducted to evaluate its efficacy in subjects with chronic low back pain. The primary efficacy variable was mean daily diary pain intensity ratings, and secondary pain intensity and relief outcomes included weekly pain intensity ratings, the McGill Pain Questionnaire (MPQ) Present Pain Intensity scale, pain relief ratings, and satisfaction with pain relief ratings. Adverse events were also assessed throughout the trial. Analyses were performed of an intention-to-treat sample of 44 patients, only 3 of whom met criteria for neuropathic low back pain. Daily and weekly pain intensity ratings, the MPQ Present Pain Intensity scale, and pain relief ratings were not significantly different following treatment with bupropion sustained release (SR) vs. placebo. These results suggest that bupropion SR was not significantly better than placebo in the treatment of patients with non-neuropathic chronic low back pain.
Perspective: Antidepressant medications that have both noradrenergic and serotonergic effects appear to have greater efficacy in patients with chronic low back pain than those with only serotonergic activity. We studied bupropion because it inhibits the reuptake of both norepinephrine and dopamine, but found no evidence of efficacy in patients with non-neuropathic chronic low back pain.