Comparison of cyclobenzaprine alone versus cyclobenzaprine plus ibuprofen in patients with acute musculoskeletal spasm and pain

Study objectives: Musculoskeletal spasm and pain is a leading cause of physician visits and a frequent cause of disability in people younger than 45 years. Many patients with musculoskeletal spasm and pain are treated only with high doses of nonsteroidal anti-inflammatory drugs (NSAIDs) without muscle relaxants. There are few published studies comparing the efficacy of a muscle relaxant alone or in combination with NSAIDs to support a specific treatment regimen. We are conducting a community-based trial comparing cyclobenzaprine 5 mg (Flexeril 5 mg) administered 3 times daily (tid) alone (Cyc5) or in combination with ibuprofen 400 mg tid (Motrin-IB; Cyc5/Ibu400) or ibuprofen 800 mg tid (Cyc5/Ibu800) to determine whether either over-the-counter or prescription doses of NSAIDs improve treatment outcomes when used in combination with a muscle relaxant. In 2 previous double-blind studies of acute muscle pain, cyclobenzaprine 5 mg tid alone was shown to have efficacy equivalent to 10 mg tid and superior to placebo, and to have fewer adverse events (principally sedation and dry mouth). We test the hypothesis that cyclobenzaprine 5 mg tid plus ibuprofen (400 or 800 mg tid) is not superior to cyclobenzaprine 5 mg tid alone in the treatment of acute muscle spasm and pain. Methods: This was a prospective, randomized, open-label, multicenter, 7-day study of Cyc5 versus Cyc5/Ibu400 or Cyc5/Ibu800 in patients with acute muscle spasm of the back or neck of 14 days' duration or less. Patients' spasm and pain were assessed using an 11-point (0 to 10) patient-rated numeric pain rating score collected by an interactive voice recognition system after 3 and 7 days of therapy. Patients were men and women aged 18 to 65 years. Results: Interim data from 316 patients with acute muscle spasm and pain who completed up to 7 days of therapy (Cyc5, n=102; Cyc5/Ibu400, n=115; Cyc5/Ibu800, n=99) were assessed at baseline and after 3 days (D3) and 7 days (D7) of therapy. The percentages of changes from baseline for muscle spasm and pain scores were as follows: spasm score changes: Cyc5: –35% D3; –55% D7; Cyc5/Ibu400: –37% D7; –59% D7; and Cyc5/Ibu800: –35% D3; –57% D7; and pain score changes: Cyc5: –32% D3; –52% D7; Cyc5/Ibu400: –33% D3; –56% D7; and Cyc5/Ibu800: –32% D3; –53% D7. All 3 treatments had statistically significant improvements from baseline after 3 and 7 days of therapy for spasm and pain ( P P Conclusion: Preliminary results indicate that all treatment arms provide similar improvements in acute muscle spasm and pain. These findings support the hypothesis that cyclobenzaprine 5 mg tid plus ibuprofen (400 or 800 mg tid) is not superior to cyclobenzaprine 5 mg tid alone in the treatment of acute muscle spasm and pain.