Low-Dose Amitriptyline May Be Effective in Reducing Low Back Pain Intensity and Disability

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Study participants were randomly assigned to receive low-dose amitriptyline or benztropine mesylate for a period of 6 months.
Study participants were randomly assigned to receive low-dose amitriptyline or benztropine mesylate for a period of 6 months.

A low dose of the antidepressant amitriptyline may represent an effective alternative to opioid medications for the treatment of chronic low back pain. Treatment with amitriptyline for 3 months was found to improve disability in a double-blind randomized clinical trial published in JAMA Internal Medicine.

Study participants with chronic nonspecific low back pain were recruited using advertising initiatives from hospitals, medical clinics, allied health clinics, and local media. Patients were randomly assigned to receive low-dose amitriptyline (25 mg/day; n=72) or benztropine mesylate (1 mg/day; active comparator; n=74) for a period of 6 months. The study's primary outcome was pain intensity at 3 and 6 months of follow-up, as assessed with a visual analog 0 to 10 scale and Descriptor Differential Scale. Disability, work absence, and hindrance were assessed using the Roland Morris Disability Questionnaire and Short Form Health and Labour Questionnaire, respectively.

Amitriptyline vs benztropine mesylate treatment led to a nonsignificant reduction in pain intensity at the 6-month follow-up (adjusted mean [standard error] reduction, 12.6±2.7 points vs 4.8±2.9 points, respectively; adjusted difference, −7.81; 95% CI, −15.7 to 0.10) and 3-month follow-up (adjusted difference, −1.05; 95% CI, −7.87 to 5.78; P =.76). Disability after 6 months of treatment was comparable between the 2 groups (adjusted difference, −0.98; 95% CI, −2.42 to 0.46; P =.18), but those who received amitriptyline had greater improvement in disability at 3 months compared with those receiving benztropine mesylate (adjusted difference, −1.62; 95% CI, −2.88 to −0.36; P =.01).

No differences were observed between the 2 groups in terms of work outcomes at 6 months (adjusted difference, absence: 1.51; 95% CI, 0.43-5.38; hindrance: 0.53; 95% CI, 0.19-1.51; P =.24) and at 3 months (adjusted difference, absence: 0.86; 95% CI, 0.32-2.31; hindrance: 0.78; 95% CI, 0.29-2.08; P =.58). The rate of adverse events leading to study withdrawal were comparable in both groups (12%; P =.95).

Limitations of the study include a small cohort and a short follow-up duration.

“It may be worth trying low-dose amitriptyline for these patients, especially if the only alternative is an opioid,” noted the study authors.

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Reference

Urquhart DM, Wluka AE, van Tulder M, et al. Efficacy of low-dose amitriptyline for chronic low back pain: a randomized clinical trial [published online October 1, 2018]. JAMA Intern Med. doi: 10.1001/jamainternmed.2018.4222

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