Effects of noradrenergic and serotonergic antidepressants on chronic low back pain intensity

To understand the relative efficacy of noradrenergic and serotonergic antid epressants as analgesics in chronic back pain without depression, we conduc ted a randomized, double-blind, placebo-control head-to-head comparison of maprotiline (a norepinephrine reuptake blocker) and paroxetine (a serotonin reuptake blocker) in 103 patients with chronic low back pain. Of these 74 completed the trial; of the 29 who did not complete, 19 were withdrawn beca use of adverse effects. The intervention consisted of an 8-week course of m aprotiline (up to 150 mg daily) or paroxetine (up to 30 mg daily) or an act ive placebo, diphenhydramine hydrochloride (up to 37.5 mg daily). Patients were excluded for current major depression. Reduction in pain intensity (De scriptor Differential Scale scores) was significantly greater for study com pleters randomized to maprotiline compared to placebo (P = 0.023), and to p aroxetine (P = 0.013), with a reduction of pain by 45% compared to 27% on p lacebo and 26% on paroxetine. These results suggest that at standard dosage s noradrenergic agents may provide more effective analgesia in back pain th an do selective serotonergic reuptake inhibitors. Published for the Interna tional Association for the Study of Pain by Elsevier Science B.V.