Ibuprofen Plus Metaxolone, Tizanidine, or Baclofen for Low Back Pain

Inclusion Criteria:

- Present to ED primary for management of LBP, defined as pain originating between the
lower border of the scapulae and the upper gluteal folds. Flank pain, that is pain
originating from tissues lateral to the paraspinal muscles, will not be included.

- Musculoskeletal etiology of low back. Patients with non-musculoskeletal etiologies
such as urinary tract infection, ovarian cysts, or influenza like illness will be
excluded. The primary clinical diagnosis, at the conclusion of the ED visit, must be a
diagnosis consistent with non-traumatic, non-radicular, musculoskeletal LBP.

- Patient is to be discharged home. Patients admitted to the hospital are more likely to
be treated with parenteral medication and therefore are not appropriate for this
study.

- Age 18-64 Enrollment will be limited to adults younger than 65 years because of the
increased risk of adverse medication effects in the elderly.

- Non-radicular pain. Patients will be excluded if the pain radiates below the gluteal
folds in a radicular pattern.

- Pain duration <2 weeks (336 hours). Patients with more than two weeks of pain are at
increased risk of poor pain and functional outcomes.(9)

- Prior to the acute attack of LBP, back pain cannot occur more frequently than once per
month. Patients with more frequent back pain are at increased risk of poor pain and
functional outcomes.(9)

- Non-traumatic LBP: no substantial and direct trauma to the back within the previous
month

- Functionally impairing back pain: A baseline score of > 5 on the Roland-Morris
Disability Questionnaire

Exclusion Criteria:

- Not available for follow-up

- Pregnant or breast-feeding

- Chronic pain syndrome defined as use of any analgesic medication on a daily or
near-daily basis

- Allergic to or intolerant of investigational medications

- Contra-indications to non-steroidal anti-inflammatory drugs: 1) history of
hypersensitivity to NSAIDs or aspirin 2) active or history of peptic ulcer disease,
chronic dyspepsia, or active or history of gastrointestinal bleed 3) Severe heart
failure (NYHA 2 or worse) 4) hypertension (JNC7 stage 2 or worse) 5) Chronic kidney
disease 3 or worse 6) Current use of anti-coagulants 7) Hepatitis 8) Alcoholism

- Contra-indications to muscle relaxants: 1) Concurrent use of centrally acting opioids;
2) Renal impairment; 3) Liver abnormality including cirrhosis or elevated enzymes 4)
Use of any of the following medications: fluvoxamine, fluoroquinolones, amiodarone,
mexiletine, propafenone, verapamil, cimetidine, famotidine, acyclovir, ticlopidine,
oral contraceptive pills