- Opioids and muscle relaxants are often prescribed alongside nonsteroidal anti-inflammatory drugs (NSAIDs) for patients with acute low back pain, although these additional medications are associated with an increased risk of adverse events.
- In patients with nontraumatic, nonradicular, acute low back pain, there were no significant differences among groups in pain or functional outcomes at 1 week or 3 months comparing the addtion of cyclobenzaprine or oxycodone/acetaminophen or placebo to naproxen.
- Naproxen alone was also associated with reduced risk of adverse events compared to either naproxen combination therapy.
The American College of Physician and the American Pain Society recommend acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) as first-line medications for patients with low back pain (Ann Intern Med 2007 Oct 2;147(7):478). However, opioids, NSAIDS, and muscle relaxants alone or in combination are commonly prescribed to patients with low back pain presenting to the emergency department (Spine (Phila Pa 1976) 2010 Nov 15;35(24):E1406). Some evidence suggests that muscle relaxants and opioid medication may improve pain in patients with acute low back pain, but these medications are also associated with an increased risk of adverse events and, with opioids in particular, there is the potential for abuse and addiction (Ann Intern Med 2007 Oct 2;147(7):478, Cochrane Database Syst Rev 2003;(2):CD004252). A recent randomized trial compared the addition of one of three regimens (cyclobenzaprine 5 mg or oxycodone 5 mg/acetaminophen 325 mg or placebo) to naproxen 500 mg twice daily in 323 adults 21-64 years old (mean age 39 years) presenting to the emergency department with nontraumatic, nonradicular, acute musculoskeletal low back pain. Patients were instructed to take 1 tablet of the randomized medication every 8 hours as needed, but they were instructed to take a second tablet if sufficient relief was not achieved within 30 minutes. All patients also received a 10 minute educational intervention discussing additional therapies to help alleviate pain.
Low back pain was assessed at baseline and during follow-up with the Roland-Morris Disability Questionnaire (RMDQ). RMDQ scores range from 0-24 with higher scores indicating increasing impairment, and all patients had a baseline RMDQ score ≥ 5 at emergency department discharge (mean score 18.7). The minimum clinically important difference in RMDQ scores at follow-up was defined as a 5 point improvement on the RMDQ. Comparing the addition of cyclobenzaprine or oxycodone/acetaminophen or placebo to naproxen, there were no significant differences in mean RMDQ score improvement at 1-week follow-up (10.1 points vs. 11.1 points vs. 9.8 points, respectively). There were also no significant differences at 1-week follow-up in mean RMDQ scores, worst low back pain, frequency of low back pain episodes, use of low back pain medication, the desire for the same medication for subsequent low back pain episodes, and time to return to usual activities. There were no significant differences among the groups in mean RMDQ score, worst pain, pain frequency, use of mediation, or opioid use at 3 months. Cyclobenzaprine and oxycodone/acetaminophen were each associated with significant increases in the rate of adverse events (sedation and gastrointestinal symptoms) compared to placebo, however. Adverse events were reported in 33% of patients randomized to cyclobenzaprine (p < 0.05 vs. placebo, NNH 7), 40% of patients randomized to oxycodone plus acetaminophen (p < 0.05 vs. placebo, NNH 5), and 21% of patients randomized to placebo.
While opioids and muscle relaxants are commonly prescribed to patients presenting with acute low back pain, based on this trial naproxen alone is as effective as combination therapy in relieving pain. These results also suggest that the addition of these medications to naproxen may place the patient at an increased risk of harm. Furthermore, approximately 25% of patients in each group still experienced moderate-to-severe low back pain at the 3-month follow-up, indicating that the initial choice of pain medication may not impact the development of chronic low back pain.