Low-dose cyclobenzaprine versus combination therapy with ibuprofen for acute neck or back pain with muscle spasm: a randomized trial

OBJECTIVE: This prospective, randomized, open-label, multicenter, community-based study was conducted to compare cyclobenzaprine 5 mg three times daily (TID) orally (CYC5) given for 7 days as monotherapy or in combination with ibuprofen 400 mg TID (CYC5/IBU400) or 800 mg TID (CYC5/IBU800) in adults with acute neck or back pain with muscle spasm. STUDY DESIGN: Eligible patients were 18-65 years old, had cervical or thoracolumbar pain and spasm for < or = 14 days, and, aside from the prescribed study medications, discontinued treatment with all analgesics, anti-inflammatory agents, and skeletal muscle relaxants during the study period. Randomization was 1:1:1 to the three treatment groups. Treatment outcome was assessed after 3 and 7 days of therapy using five patient-rated scales: spasm, pain, patient global impression of change (PGIC), medication helpfulness, and Oswestry Disability Index (ODI). RESULTS: A total of 867 patients provided postbaseline data and were included in the intent-to-treat population (CYC5, n = 288; CYC5/IBU400, n = 286; CYC5/IBU800, n = 293). All three treatment groups demonstrated significant improvements from baseline in PGIC, spasm, pain, ODI, and medication helpfulness (p < 0.001 for all comparisons) after 3 and 7 days of therapy. There were no significant differences in mean PGIC among groups after 3 days of therapy (p = 0.65 for treatment effect) or after 7 days of therapy (primary endpoint; p = 0.41). A PGIC responder analysis of changes from baseline showed that 88% and 93% of patients reported at least mild improvement after 3 and 7 days of therapy, respectively. All three treatments were well tolerated, with no significant differences between treatments regarding the number of adverse events (AEs) reported or number of patients reporting AEs. The most common AEs in all groups were fatigue, somnolence, dizziness, sedation, and nausea. Limitations of this study include an unblinded design and possible introduction of bias into efficacy and safety results by use of a voluntary telephone reporting system. CONCLUSIONS: This randomized, community-based clinical trial demonstrated that combination therapy with cyclobenzaprine 5 mg TID plus ibuprofen was not superior to cyclobenzaprine 5 mg TID alone in adult patients with acute neck and back pain with muscle spasm. All treatments were well tolerated.