A Randomized, Placebo-Controlled Trial of Ibuprofen Plus Metaxalone, Tizanidine, or Baclofen for Acute Low Back Pain

Benjamin W. Friedman, Eddie Irizarry, Clemencia Solorzano, Eleftheria Zias, Scott Pearlman, Andrew Wollowitz, Michael P. Jones, Purvi D. Shah, E. John Gallagher

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Study objective: Patients with low back pain are often treated with nonsteroidal anti-inflammatory drugs and skeletal muscle relaxants. We compare functional outcomes and pain among patients with acute low back pain who were randomized to a 1-week course of ibuprofen plus placebo versus ibuprofen plus 1 of 3 skeletal muscle relaxants: baclofen, metaxalone, and tizanidine. Methods: This was a randomized, double-blind, parallel-group, 4-arm study conducted in 2 urban emergency departments (EDs). Patients with nonradicular low back pain for less than or equal to 2 weeks were eligible if they had a score greater than 5 on the Roland-Morris Disability Questionnaire, a 24-item inventory of functional impairment caused by low back pain. All participants received 21 tablets of ibuprofen 600 mg, to be taken 3 times a day as needed. Additionally, they were randomized to baclofen 10 mg, metaxalone 400 mg, tizanidine 2 mg, or placebo. Participants were instructed to take 1 or 2 of these capsules 3 times a day as needed. All participants received a 10-minute educational session. The primary outcome was improvement on the Roland-Morris Disability Questionnaire between ED discharge and 1week later. Secondary outcomes included pain intensity 1 week after ED discharge (severe, moderate, mild, or none). Results: Three hundred twenty patients were randomized. One week later, the mean Roland-Morris Disability Questionnaire score of patients randomized to placebo improved by 11.1 points (95% confidence interval [CI] 9.0 to 13.3), baclofen by 10.6 points (95% CI 8.6 to 12.7), metaxalone by 10.1 points (95% CI 8.0 to 12.3), and tizanidine by 11.2 points (95% CI 9.2 to 13.2). At 1-week follow-up, 30% of placebo patients (95% CI 21% to 41%) reported moderate to severe low back pain versus 33% of baclofen patients (95% CI 24% to 44%), 37% of metaxalone patients (95% CI 27% to 48%), and 33% of tizanidine patients (95% CI 23% to 44%). Conclusion: Adding baclofen, metaxalone, or tizanidine to ibuprofen does not appear to improve functioning or pain any more than placebo plus ibuprofen by 1 week after an ED visit for acute low back pain.

Original languageEnglish (US)
Pages (from-to)512-520
Number of pages9
JournalAnnals of emergency medicine
Issue number4
StatePublished - Oct 2019

ASJC Scopus subject areas

  • Emergency Medicine


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